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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds meaningful behavior beyond that: the 404 error condition when a CIK is absent from the dataset, plus a concrete inventory of what the response contains.

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 the return contract and payload contents, then the error case, then the alternative tool — a sensible order with little waste. The cik example sentence duplicates the schema verbatim, which is the only mildly redundant element.

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, the description need not detail return values, and it still summarizes the payload categories and the 404 case. Complete enough for a single-parameter, read-only lookup.

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% and the single `cik` parameter is fully documented in the schema, including the identical zero-padded examples. The description restates the same example rather than adding format nuance, so it does not exceed the baseline.

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 ('Returns one SEC-reporting company') and resource ('by CIK') and pins the dataset id `sec-companies`. It also enumerates the payload's contents (filing-history summary, financial rollups, 90-day insider activity), which clearly distinguishes it from the search/facets 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?

Explicitly routes the agent to datasets_sec_companies_search for searching the same dataset, giving a clear when-not-to-use-this signal. It does not address the sibling tools that expose financials and insider data separately, which is a minor gap given this tool bundles rollups of those.

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