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

Annotations only declare read-only and closed-world; the description adds substantial behavioral context beyond them: append-only archive, Starter/Pro tier limits, 90-day window cap, per-page row limit, daily fair-use call quotas, 1-hour throttling with 429, bulk licensing, and API-key requirement.

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?

Front-loads purpose, then presents constraints (window, pagination, rate limits, licensing, auth) in a compact block. Every sentence adds operative information for correct invocation; no filler or repetition.

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 read-only tool with no output schema, the definition covers access scope, pagination, rate limits, tiering, licensing, and auth. It lacks explicit return-field detail and does not route to close siblings like lookup_entity, so it is strong but not perfect.

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 67%, so schema already documents most parameter details. The description adds meaningful constraints beyond the schema: 'ONE entity' (singular scope), explicit 90-day from/to window, cursor pagination flow, and an effective page-row cap; feed enum semantics remain only in the schema.

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: 'Daily time series for ONE entity from the append-only archive.' The 'ONE entity' and 'No whole-feed dumps' wording cleanly distinguishes it from whole-feed siblings like get_trends or get_momentum_leaderboard.

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 clear when-to-use constraints (max 90-day window, pagination via cursor, no whole-feed dumps, tier caps) and when-not (bulk access requires separate licence). Does not explicitly name an alternative sibling tool to use instead, so falls short of a 5.

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