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

Annotations only supply the safety profile (destructive=true, non-idempotent); the description goes well beyond by disclosing the async contract (returns task_id immediately, completion/failure posted to chat, get_task_status for progress), the plan-quota cost, the source_text rebuild behavior, and specific error codes ('not_found', 'limit_exceeded', 'invalid_payload').

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?

Dense but front-loaded: purpose first, then async contract, then when/when-not, then source_text semantics, then error codes. Every sentence carries information, though the single long paragraph could be broken into shorter clauses for faster scanning.

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 an output schema present, return values need not be explained, and the description nonetheless covers the async lifecycle, quota consumption, failure modes, and unsupported operations. An agent has everything needed to invoke and interpret the call.

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 describes all three fields, but the description adds real meaning beyond it: it clarifies that source_text is used verbatim and switches the tool from edit-mode to rebuild-mode ('the resume is then rebuilt from that text instead of being edited from the instruction'), plus restates the 20000-char cap and the consequence of paraphrasing.

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?

Opens with a specific verb+resource ('Rewrite a resume from a natural-language instruction') and immediately scopes it against siblings: small structural edits are update_resume_section, translation is translate_resume. An agent can distinguish it from every other resume tool without opening a schema.

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?

Explicit when-to-use with concrete examples ('rewrite my summary for a senior role', 'tighten all bullets'), explicit when-not (small structural edits -> update_resume_section), and named alternatives for unsupported cases (translate_resume). Nothing is left to inference.

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