diff --git a/examples/functions.ts b/examples/functions.ts
index 8b239b08..99a070ac 100644
--- a/examples/functions.ts
+++ b/examples/functions.ts
@@ -2,16 +2,21 @@ import { OpenAIClient } from '@agentic/openai-fetch'
 import 'dotenv/config'
 import { z } from 'zod'
 
-import { Agentic, CalculatorTool } from '@/index'
+import { Agentic, CalculatorTool, WeatherTool } from '@/index'
 
 async function main() {
   const openai = new OpenAIClient({ apiKey: process.env.OPENAI_API_KEY! })
   const agentic = new Agentic({ openai })
 
   const example = await agentic
-    .gpt3('What is 5 * 50?')
-    .tools([new CalculatorTool({ agentic })])
-    .output(z.object({ answer: z.number() }))
+    .gpt3('What is the temperature in san francisco today?')
+    .tools([new CalculatorTool(), new WeatherTool()])
+    .output(
+      z.object({
+        answer: z.number(),
+        units: z.union([z.literal('fahrenheit'), z.literal('celcius')])
+      })
+    )
     .call()
   console.log(example)
 }
diff --git a/package.json b/package.json
index 82fd944c..9bb4e975 100644
--- a/package.json
+++ b/package.json
@@ -101,7 +101,7 @@
     ]
   },
   "ava": {
-    "snapshotDir": ".snapshots",
+    "snapshotDir": "test/.snapshots",
     "extensions": {
       "ts": "module"
     },
diff --git a/src/agentic.ts b/src/agentic.ts
index dcd757b4..67e9a923 100644
--- a/src/agentic.ts
+++ b/src/agentic.ts
@@ -1,11 +1,10 @@
-import * as types from '@/types'
-import { DEFAULT_OPENAI_MODEL } from '@/constants'
-import { OpenAIChatCompletion } from '@/llms/openai'
-
+import * as types from './types'
+import { DEFAULT_OPENAI_MODEL } from './constants'
 import {
   HumanFeedbackMechanism,
   HumanFeedbackMechanismCLI
 } from './human-feedback'
+import { OpenAIChatCompletion } from './llms/openai'
 import { defaultIDGeneratorFn } from './utils'
 
 export class Agentic {
@@ -20,7 +19,9 @@ export class Agentic {
     'provider' | 'model' | 'modelParams' | 'timeoutMs' | 'retryConfig'
   >
   protected _defaultHumanFeedbackMechamism?: HumanFeedbackMechanism
+
   protected _idGeneratorFn: types.IDGeneratorFunction
+  protected _id: string
 
   constructor(opts: {
     openai?: types.openai.OpenAIClient
@@ -33,6 +34,10 @@ export class Agentic {
     defaultHumanFeedbackMechanism?: HumanFeedbackMechanism
     idGeneratorFn?: types.IDGeneratorFunction
   }) {
+    if (!globalThis.__agentic?.deref()) {
+      globalThis.__agentic = new WeakRef(this)
+    }
+
     this._openai = opts.openai
     this._anthropic = opts.anthropic
 
@@ -59,6 +64,7 @@ export class Agentic {
       new HumanFeedbackMechanismCLI({ agentic: this })
 
     this._idGeneratorFn = opts.idGeneratorFn ?? defaultIDGeneratorFn
+    this._id = this._idGeneratorFn()
   }
 
   public get openai(): types.openai.OpenAIClient | undefined {
diff --git a/src/human-feedback.ts b/src/human-feedback.ts
index 40c1d5a3..6f9e3d2d 100644
--- a/src/human-feedback.ts
+++ b/src/human-feedback.ts
@@ -1,6 +1,6 @@
-import * as types from '@/types'
-import { Agentic } from '@/agentic'
-import { BaseTask } from '@/task'
+import * as types from './types'
+import { Agentic } from './agentic'
+import { BaseTask } from './task'
 
 export type HumanFeedbackType = 'confirm' | 'selectOne' | 'selectN'
 
diff --git a/src/llms/anthropic.ts b/src/llms/anthropic.ts
index 52a21c74..2a267cdd 100644
--- a/src/llms/anthropic.ts
+++ b/src/llms/anthropic.ts
@@ -38,7 +38,7 @@ export class AnthropicChatCompletion<
       ...options
     })
 
-    if (this._agentic.anthropic) {
+    if (this._agentic?.anthropic) {
       this._client = this._agentic.anthropic
     } else {
       throw new Error(
diff --git a/src/llms/chat.ts b/src/llms/chat.ts
index acd925e8..9ab4aa1c 100644
--- a/src/llms/chat.ts
+++ b/src/llms/chat.ts
@@ -72,13 +72,38 @@ export abstract class BaseChatCompletion<
     }
 
     this._tools = tools
+    for (const tool of tools) {
+      tool.agentic = this.agentic
+    }
+
     return this
   }
 
+  /**
+   * Whether or not this chat completion model directly supports the use of tools.
+   */
   public get supportsTools(): boolean {
     return false
   }
 
+  public override validate() {
+    super.validate()
+
+    if (this._tools) {
+      for (const tool of this._tools) {
+        if (!tool.agentic) {
+          tool.agentic = this.agentic
+        } else if (tool.agentic !== this.agentic) {
+          throw new Error(
+            `Task "${this.nameForHuman}" has a different Agentic runtime instance than the tool "${tool.nameForHuman}"`
+          )
+        }
+
+        tool.validate()
+      }
+    }
+  }
+
   protected abstract _createChatCompletion(
     messages: types.ChatMessage[],
     functions?: types.openai.ChatMessageFunction[]
@@ -133,9 +158,22 @@ export abstract class BaseChatCompletion<
           .replace(/^ {4}/gm, '  ')
           .replace(/;$/gm, '')
 
+        const label =
+          this._outputSchema instanceof z.ZodArray
+            ? 'JSON array'
+            : this._outputSchema instanceof z.ZodObject
+            ? 'JSON object'
+            : this._outputSchema instanceof z.ZodNumber
+            ? 'number'
+            : this._outputSchema instanceof z.ZodString
+            ? 'string'
+            : this._outputSchema instanceof z.ZodBoolean
+            ? 'boolean'
+            : 'JSON value'
+
         messages.push({
           role: 'system',
-          content: dedent`Do not output code. Output JSON only in the following TypeScript format:
+          content: dedent`Do not output code. Output a single ${label} in the following TypeScript format:
           \`\`\`ts
           ${tsTypeString}
           \`\`\``
@@ -285,6 +323,11 @@ export abstract class BaseChatCompletion<
         try {
           const trimmedOutput = extractJSONObjectFromString(output)
           output = JSON.parse(jsonrepair(trimmedOutput ?? output))
+
+          if (Array.isArray(output)) {
+            // TODO
+            output = output[0]
+          }
         } catch (err: any) {
           if (err instanceof JSONRepairError) {
             throw new errors.OutputValidationError(err.message, { cause: err })
diff --git a/src/llms/openai.ts b/src/llms/openai.ts
index 1ec90238..ee8f5017 100644
--- a/src/llms/openai.ts
+++ b/src/llms/openai.ts
@@ -38,7 +38,7 @@ export class OpenAIChatCompletion<
       ...options
     })
 
-    if (this._agentic.openai) {
+    if (this._agentic?.openai) {
       this._client = this._agentic.openai
     } else {
       throw new Error(
@@ -93,6 +93,30 @@ export class OpenAIChatCompletion<
     return openaiModelsSupportingFunctions.has(this._model)
   }
 
+  public override validate() {
+    super.validate()
+
+    if (!this._client) {
+      throw new Error(
+        'OpenAIChatCompletion requires an OpenAI client to be configured on the Agentic runtime'
+      )
+    }
+
+    if (!this.supportsTools) {
+      if (this._tools) {
+        throw new Error(
+          `This OpenAI chat model "${this.nameForHuman}" does not support tools`
+        )
+      }
+
+      if (this._modelParams?.functions) {
+        throw new Error(
+          `This OpenAI chat model "${this.nameForHuman}" does not support functions`
+        )
+      }
+    }
+  }
+
   protected override async _createChatCompletion(
     messages: types.ChatMessage[],
     functions?: types.openai.ChatMessageFunction[]
diff --git a/src/task.ts b/src/task.ts
index e6f504a0..b0b98131 100644
--- a/src/task.ts
+++ b/src/task.ts
@@ -1,9 +1,10 @@
 import pRetry, { FailedAttemptError } from 'p-retry'
 import { ZodType } from 'zod'
 
-import * as errors from '@/errors'
-import * as types from '@/types'
-import { Agentic } from '@/agentic'
+import * as errors from './errors'
+import * as types from './types'
+import type { Agentic } from './agentic'
+import { defaultIDGeneratorFn, isValidTaskIdentifier } from './utils'
 
 /**
  * A `Task` is an async function call that may be non-deterministic. It has
@@ -28,24 +29,27 @@ export abstract class BaseTask<
   protected _timeoutMs?: number
   protected _retryConfig: types.RetryConfig
 
-  constructor(options: types.BaseTaskOptions) {
-    if (!options.agentic) {
-      throw new Error('Passing "agentic" is required when creating a Task')
-    }
+  constructor(options: types.BaseTaskOptions = {}) {
+    this._agentic = options.agentic ?? globalThis.__agentic?.deref()
 
-    this._agentic = options.agentic
     this._timeoutMs = options.timeoutMs
     this._retryConfig = options.retryConfig ?? {
       retries: 3,
       strategy: 'default'
     }
-    this._id = options.id ?? this._agentic.idGeneratorFn()
+
+    this._id =
+      options.id ?? this._agentic?.idGeneratorFn() ?? defaultIDGeneratorFn()
   }
 
   public get agentic(): Agentic {
     return this._agentic
   }
 
+  public set agentic(agentic: Agentic) {
+    this._agentic = agentic
+  }
+
   public get id(): string {
     return this._id
   }
@@ -53,7 +57,10 @@ export abstract class BaseTask<
   public abstract get inputSchema(): ZodType<TInput>
   public abstract get outputSchema(): ZodType<TOutput>
 
-  public abstract get nameForModel(): string
+  public get nameForModel(): string {
+    const name = this.constructor.name
+    return name[0].toLowerCase() + name.slice(1)
+  }
 
   public get nameForHuman(): string {
     return this.constructor.name
@@ -63,6 +70,19 @@ export abstract class BaseTask<
     return ''
   }
 
+  public validate() {
+    if (!this._agentic) {
+      throw new Error(
+        `Task "${this.nameForHuman}" is missing a required "agentic" instance`
+      )
+    }
+
+    const nameForModel = this.nameForModel
+    if (!isValidTaskIdentifier(nameForModel)) {
+      throw new Error(`Task field nameForModel "${nameForModel}" is invalid`)
+    }
+  }
+
   // TODO: is this really necessary?
   public clone(): BaseTask<TInput, TOutput> {
     // TODO: override in subclass if needed
@@ -88,6 +108,8 @@ export abstract class BaseTask<
   public async callWithMetadata(
     input?: TInput
   ): Promise<types.TaskResponse<TOutput>> {
+    this.validate()
+
     if (this.inputSchema) {
       const safeInput = this.inputSchema.safeParse(input)
 
@@ -104,7 +126,7 @@ export abstract class BaseTask<
       metadata: {
         taskName: this.nameForModel,
         taskId: this.id,
-        callId: this._agentic.idGeneratorFn()
+        callId: this._agentic!.idGeneratorFn()
       }
     }
 
diff --git a/src/tools/calculator.ts b/src/tools/calculator.ts
index 6850374d..82a0aef6 100644
--- a/src/tools/calculator.ts
+++ b/src/tools/calculator.ts
@@ -19,7 +19,7 @@ export class CalculatorTool extends BaseTask<
   CalculatorInput,
   CalculatorOutput
 > {
-  constructor(opts: types.BaseTaskOptions) {
+  constructor(opts: types.BaseTaskOptions = {}) {
     super(opts)
   }
 
diff --git a/src/tools/metaphor.ts b/src/tools/metaphor.ts
index 0dec2821..7cf00f75 100644
--- a/src/tools/metaphor.ts
+++ b/src/tools/metaphor.ts
@@ -1,26 +1,20 @@
 import * as metaphor from '@/services/metaphor'
 import * as types from '@/types'
-import { Agentic } from '@/agentic'
 import { BaseTask } from '@/task'
 
 export class MetaphorSearchTool extends BaseTask<
   metaphor.MetaphorSearchInput,
   metaphor.MetaphorSearchOutput
 > {
-  _metaphorClient: metaphor.MetaphorClient
+  protected _metaphorClient: metaphor.MetaphorClient
 
   constructor({
-    agentic,
     metaphorClient = new metaphor.MetaphorClient(),
-    ...rest
+    ...opts
   }: {
-    agentic: Agentic
     metaphorClient?: metaphor.MetaphorClient
-  } & types.BaseTaskOptions) {
-    super({
-      agentic,
-      ...rest
-    })
+  } & types.BaseTaskOptions = {}) {
+    super(opts)
 
     this._metaphorClient = metaphorClient
   }
@@ -34,7 +28,7 @@ export class MetaphorSearchTool extends BaseTask<
   }
 
   public override get nameForModel(): string {
-    return 'metaphor_web_search'
+    return 'metaphorWebSearch'
   }
 
   protected override async _call(
diff --git a/src/tools/novu.ts b/src/tools/novu.ts
index 2fec0283..46b9ec71 100644
--- a/src/tools/novu.ts
+++ b/src/tools/novu.ts
@@ -1,7 +1,6 @@
 import { z } from 'zod'
 
 import * as types from '@/types'
-import { Agentic } from '@/agentic'
 import { NovuClient } from '@/services/novu'
 import { BaseTask } from '@/task'
 
@@ -39,18 +38,15 @@ export class NovuNotificationTool extends BaseTask<
   NovuNotificationToolInput,
   NovuNotificationToolOutput
 > {
-  _novuClient: NovuClient
+  protected _novuClient: NovuClient
 
   constructor({
-    agentic,
-    novuClient = new NovuClient()
+    novuClient = new NovuClient(),
+    ...opts
   }: {
-    agentic: Agentic
     novuClient?: NovuClient
-  }) {
-    super({
-      agentic
-    })
+  } & types.BaseTaskOptions = {}) {
+    super(opts)
 
     this._novuClient = novuClient
   }
@@ -64,7 +60,7 @@ export class NovuNotificationTool extends BaseTask<
   }
 
   public override get nameForModel(): string {
-    return 'novu_send_notification'
+    return 'novuSendNotification'
   }
 
   protected override async _call(
diff --git a/src/tools/weather.ts b/src/tools/weather.ts
index f84c45f9..58edc322 100644
--- a/src/tools/weather.ts
+++ b/src/tools/weather.ts
@@ -9,7 +9,12 @@ export const WeatherInputSchema = z.object({
     .string()
     .describe(
       'Location to get the weather for. Can be a city name like "Paris", a zipcode like "53121", an international postal code like "SW1", or a latitude and longitude like "48.8567,2.3508"'
-    )
+    ),
+
+  units: z
+    .union([z.literal('imperial'), z.literal('metric')])
+    .default('imperial')
+    .optional()
 })
 export type WeatherInput = z.infer<typeof WeatherInputSchema>
 
@@ -33,8 +38,8 @@ const ConditionSchema = z.object({
 const CurrentSchema = z.object({
   last_updated_epoch: z.number(),
   last_updated: z.string(),
-  temp_c: z.number(),
-  temp_f: z.number(),
+  temp_c: z.number().describe('temperature in celsius'),
+  temp_f: z.number().describe('temperature in fahrenheit'),
   is_day: z.number(),
   condition: ConditionSchema,
   wind_mph: z.number(),
@@ -65,14 +70,19 @@ export type WeatherOutput = z.infer<typeof WeatherOutputSchema>
 export class WeatherTool extends BaseTask<WeatherInput, WeatherOutput> {
   client: WeatherClient
 
-  constructor(
-    opts: {
-      weather: WeatherClient
-    } & types.BaseTaskOptions
-  ) {
+  constructor({
+    weather = new WeatherClient({ apiKey: process.env.WEATHER_API_KEY }),
+    ...opts
+  }: {
+    weather?: WeatherClient
+  } & types.BaseTaskOptions = {}) {
     super(opts)
 
-    this.client = opts.weather
+    if (!weather) {
+      throw new Error(`Error WeatherTool missing required "weather" client`)
+    }
+
+    this.client = weather
   }
 
   public override get inputSchema() {
@@ -92,7 +102,7 @@ export class WeatherTool extends BaseTask<WeatherInput, WeatherOutput> {
   }
 
   public override get descForModel(): string {
-    return 'Useful for getting the current weather at a location'
+    return 'Useful for getting the current weather at a location.'
   }
 
   protected override async _call(
diff --git a/src/types.ts b/src/types.ts
index 37c16bbf..c18c2269 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -20,7 +20,7 @@ export type SafeParsedData<T extends ZodTypeAny> = T extends ZodTypeAny
   : never
 
 export interface BaseTaskOptions {
-  agentic: Agentic
+  agentic?: Agentic
 
   timeoutMs?: number
   retryConfig?: RetryConfig
diff --git a/.snapshots/test/llms/llm-utils.test.ts.md b/test/.snapshots/test/llms/llm-utils.test.ts.md
similarity index 100%
rename from .snapshots/test/llms/llm-utils.test.ts.md
rename to test/.snapshots/test/llms/llm-utils.test.ts.md
diff --git a/.snapshots/test/llms/llm-utils.test.ts.snap b/test/.snapshots/test/llms/llm-utils.test.ts.snap
similarity index 100%
rename from .snapshots/test/llms/llm-utils.test.ts.snap
rename to test/.snapshots/test/llms/llm-utils.test.ts.snap