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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is known. The description adds genuinely new context beyond them: it discloses the authentication requirement ('No account needed') and summarizes the categories of data returned, which matters because there is no output schema. It stops short of describing rate limits, caching, or response structure.

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?

A single tight sentence that front-loads the resource and packs the full scope of returned information, followed by the one-line auth note. Every clause earns its place; nothing is redundant with the tool name.

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?

With no parameters and no output schema, the description carries the burden of telling the agent what comes back, and it does so by enumerating the data categories. Combined with the auth note, an agent has everything needed to decide to call it and to interpret the result.

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 tool takes zero parameters, so the schema has nothing to explain and the baseline of 4 applies. The description correctly does not invent parameters or imply any input is required.

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?

Names a specific verb ('Returns') and enumerates the exact resource contents: prices, credit rules, free allowances, upload and link limits, supported inputs and export formats. This is unambiguous and cannot be confused with the sibling tools (get_transcript, list_transcripts, transcribe_url), which all operate on transcript data rather than reference information.

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?

'No account needed' gives useful context about prerequisites for calling it, implying it is a safe pre-flight lookup. However, there is no explicit when-to-use guidance, such as calling it before transcription to verify credit allowances or upload limits, and no stated alternatives or exclusions.

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