update_texttrack

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

Annotations already carry the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), and the description's mutation verbs are consistent with them—no contradiction. The description adds that there are three distinct modification modes (rename, language, active), but does not disclose whether updates are partial, whether setting active unsets the previous default track, or what side effects a language change has on transcripts. Moderate value beyond annotations.

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 14-word sentence that front-loads operations with action verbs ('Rename... change... make active') and contains zero redundant content. Every word earns its place.

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?

For a 5-param mutation tool with 60% schema coverage and no output schema, the description covers the core semantics but leaves gaps: whether rename and language change can be combined in one call, whether setting active=true is exclusive, and what the response indicates about success. Adequate for basic invocation, thin on side effects and combination rules.

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 schema documents only video_id and track_id, leaving name, active, and language undocumented (60% coverage). The description compensates directly by mapping each undocumented param to an action: rename→name, change language→language, make active→active. This gives the agent semantic meaning the schema alone fails to provide.

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 names a specific resource (caption track) and three concrete operations (rename, change language, make active), with action verbs that clearly identify this as the modification tool for text tracks. It doesn't explicitly name siblings, but the enumerated operations effectively distinguish it from upload_texttrack and delete_texttrack in the sibling set.

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 no guidance on when to use this tool versus alternatives like upload_texttrack or delete_texttrack, and contains no exclusions or conditions. The only prerequisite hint (track_id 'from list_texttracks') lives in the schema, not the description. Usage context is purely implied by the tool's name and operation list.

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