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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false; the description reinforces this with 'takes no parameters and changes nothing' and adds genuinely new context by itemizing the return payload (pricing, limits, privacy). It omits any auth or rate-limit detail, so not a 5.

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?

Two sentences, front-loaded with the call-first trigger before the payload inventory. The field enumeration is dense but justified given there is no output schema to carry that information.

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 output schema in the definition, the description must characterize the return value itself, and it does so by naming every top-level section. Nothing an agent needs to call a zero-parameter discovery tool is missing.

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?

Zero parameters, so the baseline is 4; the description confirms this explicitly with 'Takes no parameters,' which removes any ambiguity an agent might have about passing optional input.

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?

States a specific verb and resource ('Returns one JSON object' describing the convert.express service) and enumerates the payload sections, so an agent knows exactly what it gets back. It also positions itself against the siblings by framing itself as the discovery tool to consult before estimate_cost/start_transcription.

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?

Gives three concrete triggering conditions: new to the service, before quoting a price, or when unsure about file/link/language support. That implicitly routes pricing to estimate_cost and capability questions here, but no sibling is named explicitly, which keeps it short of a full 5.

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