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

With no annotations, the description carries the full burden and does substantial work: it discloses the upstream data source, public-domain licensing, no API key with x402 payment ($0.003/call), that failed lookups and upstream errors are free, and that the freshest of several standard us-gaap tags is chosen with an ifrs-full fallback. It stops short of rate limits or partial-failure behavior.

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?

A single dense paragraph, front-loaded with what the tool returns before the return-shape and billing details. Every sentence contributes something an agent needs, given there is no output schema.

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 paid, no-output-schema tool the description covers data source, return fields, tag selection and billing sufficiently to call it correctly. Minor gaps are error handling for invalid tickers/CIKs and whether non-US IFRS filers are fully supported.

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%, so company, metrics, annual_periods and quarterly_periods are already documented in the schema; the description only reiterates that metrics is an optional subset. Baseline 3 applies since the schema does the heavy lifting.

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?

Names a specific resource (key financials from a company's XBRL filings via SEC companyconcept) and enumerates the exact metric set returned, so an agent can immediately tell this apart from filing_text, recent_filings and company_lookup.

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?

Usage is only implied by the metric list; there is no explicit statement of when to prefer this over company_lookup or filing_text, and no noted limitations beyond the charging caveat. The 'Optional metrics subset' phrase hints at narrowing scope but leaves the choice to inference.

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