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

Annotations already declare readOnlyHint=true, and the description adds real behavioral context beyond that: a paid key is required and not yet on sale, unpublished tickers return evidence_not_published, and congressional-trade coverage is explicitly excluded. It could go further on return shape (e.g., volume or pagination of documents), but the access and failure-mode disclosures are genuinely useful.

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?

Well front-loaded: access requirement first, then what is returned, then the usage rationale, then the exclusion. Nearly every sentence earns its place, though the 'not on sale yet' remark and the redirect form a slightly dense closing run.

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?

No output schema exists, yet the description still conveys return contents (source documents plus originating filing), the not-published error case, coverage limits, and the key requirement. An agent has everything needed to decide and call correctly.

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?

With one parameter at 100% schema description coverage, the schema already documents 'ticker' with an example, so the baseline is 3. The description adds only indirect parameter behavior — the evidence_not_published outcome for tickers without published evidence — and no format or normalization guidance.

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: it returns the primary source documents (Form 4s, institutional holdings, macro series) behind a ticker's signals, with the originating filing where available. That is far more specific than the sibling list tools and lets an agent tell it apart 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?

Gives an explicit rationale ('use this to cite a claim rather than assert it') plus a concrete exclusion and redirect: congressional trades are not included, use list_congress_trades instead, which works on every key. Access conditions (paid key required, not yet on sale) are also stated up front.

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