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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and the description is fully consistent with them — no contradiction. The description adds substantial value beyond annotations: SEC-only availability, 404 when no equity statement exists, the 28-credit cost debited even on failure/missing/SEC-exclusion, and the light_weight_mode tradeoff. This is rich behavioral context.

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?

Dense but front-loaded with the core purpose in the first clause, followed by identification, scope, cost, and endpoint. Every sentence is functional — no filler or repetition of schema content. Slightly long, but each clause earns its place given the failure modes and cost disclosure it must carry.

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 no output schema, the description must explain the return value, and it does ('extracted line items with values and periods'). It covers identification, failure mode (404), scope (SEC-only), cost, and the leaner-payload option. Adequate for a read-only data fetch; the only unstated item is the precise response envelope, which is minor.

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 description coverage is 100% and every parameter already has a meaningful description, so the baseline is 3. The description adds value beyond the schema by explaining the filing_id-vs-(ticker+fiscal_year) identification tradeoff and clarifying the light_weight_mode effect ('drops the most verbose nested fields'). Minor but genuine additive value over 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?

Opens with a specific verb+resource: "Return the filing's Statement of Stockholders' (or Shareholders') Equity — its extracted line items with values and periods." It names exactly what is returned and clearly distinguishes this from the many sibling statement tools by stating it is a 'fixed shortcut for get_filing_statement(statement_type='Stockholders Equity')' and by omitting role_label/statement_type.

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 prescribes how to identify the filing (filing_id OR ticker + fiscal_year + optional quarter), declares the SEC-only scope, states the 404-on-missing behavior, and names the exact alternative (get_filing_statement) it is a shortcut for. No inference is required to decide when to use this tool.

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