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

Adds substantial context beyond the annotations: exact preservation semantics (timestamps, cue order, indices and ASS event fields untouched, only cue text translated), synchronous execution, and a 3-credit cost charged by mcp-credit-gateway before forwarding. This tells the agent about billing side effects and the blast radius of the operation, which the hints (destructiveHint=false, openWorldHint=true) do not convey.

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?

Three short sentences, each carrying distinct load: capability and formats, transformation guarantees, then cost/execution model. Front-loaded with the identifying information and free of filler.

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, the description still covers input limits, transformation behavior, sync vs async, and billing, which is most of what an agent needs. The one gap is the return shape — whether it returns translated subtitle text, a job handle, or usage metadata — which is left implicit.

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?

Schema coverage is 100%, so the baseline is 3, but the description earns a bump by explaining what happens to subtitle_content — timestamps and structural fields are preserved, only cue text is translated — which is semantics the schema cannot express. It does not add anything on 'to'/'from'/'idempotency_key' beyond the schema, keeping it out of 5 territory.

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 (translate subtitle content) plus the exact accepted formats (SRT, WebVTT, ASS/SSA), which cleanly separates it from translate_document, translate_text and translate_image. An agent can route on this line alone.

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 formats imply the use case (you have raw subtitle text), and the 1,000,000-character limit plus the synchronous note give practical context. However, there is no explicit guidance on when to prefer this over translate_document or translate_text, and no exclusion stating that binary/file inputs belong elsewhere.

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