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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds real behavioral value by stating 'Missing regional evidence is not invented' and emphasizing 'documented' notes, telling the agent the tool will not fabricate coverage gaps—a meaningful trait beyond the 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?

Two tight sentences with no filler; the core behavior is front-loaded and the anti-fabrication caveat follows as useful second-position context. It could be marginally sharper about the exact-match constraint, but nothing is wasted.

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 one-parameter lookup with no output schema, the description does the important work of telling the agent what is returned (regional/register/disambiguation notes) and that gaps are not invented. It stops short of describing the response's shape or how multi-region notes are presented, but the core is covered.

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?

There is a single parameter with 100% schema coverage, so the schema already documents 'term' (specifying 'Exact term or alias,' length bounds). The description's 'exact term' adds nothing beyond that, so the baseline of 3 for a fully-covered schema applies.

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 gives a specific verb+resource: it returns 'documented regional, register, and disambiguation notes for an exact term,' which tells an agent exactly what content comes back. However, it never distinguishes itself from the sibling lookup_term, and the name 'compare_usage' implies cross-variant comparison that the single-term, notes-returning description does not explain.

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?

There is no explicit when-to-use, no when-not-to-use, and no named alternative among decode_phrase, lookup_term, search_terms, etc. The phrase 'for an exact term' is a soft input hint (use it for exact matches, not fuzzy search) but stops well short of routing guidance.

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