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

Annotations already disclose readOnly, openWorld, idempotent, and non-destructive behavior. The description adds meaningful context beyond those annotations: results are ordered newest first, rows include data-quality flags, and unpaid calls return a payment-required error. This gives the agent useful operational expectations without contradicting 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 three sentences and every sentence earns its place: first defines the payload and ordering, second gives usage direction and the key alternative, third notes cost and failure behavior. It is front-loaded with the most important identifying information and contains no filler.

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?

Given the rich input schema, safety annotations, and stated output schema, the description covers all necessary operational context: what data is returned, how it is ordered, when to use it versus company_financials, and the payment-required error condition. There is no critical gap an agent would need to fill before invoking this 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 description coverage is 100%, and each parameter is already well documented with examples, defaults, bounds, and guidance. The tool description itself does not add extra parameter semantics, but because the schema carries the full burden, the baseline of 3 is appropriate.

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 exactly what the tool returns: raw normalized XBRL facts for one company, newest first, with a concrete list of fields. It also distinguishes itself from company_financials, which provides clean annual statements and ratios. This leaves no ambiguity about the tool's role among its 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 explicitly tells when to use this tool: 'for individual reported values, quarterly figures or filing provenance.' It also names the alternative, company_financials, and the condition for choosing it instead, making the routing decision explicit. The schema param description further advises calling lookup_company first when only a ticker or name is available.

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