Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=false, and destructiveHint=false. The description adds pricing ($0.01/call), payment methods (x402 USDC or card key), and reinforces that repeats are charged despite being read-only. This extra context about cost and idempotency is valuable beyond the annotations, though it could go further on failure behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the core purpose and return values, followed by practical details. Every sentence contributes value, though the inclusion of pricing and payment methods makes it slightly dense for a simple transcription tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's simplicity (one parameter, no output schema), the description covers all essential aspects: purpose, return values, input constraints, use cases, pricing, and idempotency. An agent has everything needed to invoke it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% description coverage for the single 'url' parameter, specifying it must be an absolute http(s) URL up to 5 MB. The description adds a concrete example URL and lists accepted audio formats (MP3, WAV, M4A, OGG), which provides useful meaning beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Transcribe speech') and resource ('audio file at a public URL') and names the underlying model (Whisper large-v3-turbo). It clearly distinguishes from siblings like ai_chat or ai_translate by focusing on audio transcription, though it doesn't explicitly name an alternative tool (e.g., ai_speech) for comparison.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear usage contexts ('voice notes, podcast clips, meeting snippets and voice messages') and defines accepted formats and size limits. However, it lacks explicit when-not-to-use guidance or named alternatives for related tasks.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.