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

Annotations already provide readOnlyHint, idempotentHint, destructiveHint=false. The description adds behavior beyond annotations: cost of 30 credits per call, that 404 and 403 are still charged, plan requirement (Starter or higher), as_of_date behavior (404 EVENTS_FILING_NOT_YET_FILED), and the _warnings field for omitted sections/differences/unresolved amendments. This is rich, valuable transparency 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?

The description is dense but efficiently structured: opening sentence, then field-by-field guidance, then cost/error/plan notes. Every sentence carries useful information. It could be slightly more scannable with bullet points, but it is appropriately sized and front-loaded with the core purpose.

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?

The description covers purpose, selection source, parameter effects, cost, errors, plan requirement, warnings, and endpoint. With no output schema present, it doesn't describe the return value shape beyond mentioning section summaries, source links, and history, which is adequate. The only minor gap is not describing what the response object looks like structurally, but the description is otherwise complete for a correctly-callable tool.

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 baseline is 3, but the description adds meaning beyond the schema: it explains the effect of items ('selects sections only; filing metadata and amendment history remain complete'), that include_original_raw_text returns raw_text at no extra cost, that include_exhibits includes attachments too, and that as_of_date yields a 404 if not yet filed. This is meaningful value beyond 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?

The description states a specific verb and resource ('Read one corporate event filing') and distinguishes it from siblings by requiring an id from list_event_filings or search_events. It also clarifies the resource is a single filing, differentiating it from list/compare/search siblings.

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 gives clear context: id comes from list_event_filings or search_events, and it explains optional behaviors (items, include_original_raw_text, include_exhibits, as_of_date). It doesn't explicitly say when NOT to use it vs alternatives, but the source-id requirement plus the detailed field behavior makes usage fairly clear.

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