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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, lowering the burden on the description. The description adds useful behavioral context beyond annotations by noting the row-per-fiscal-year structure, the $0.02 cost, and the payment-required error for unpaid calls, which helps agents anticipate failures.

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 compact and front-loaded: it first states what the tool returns, then gives usage routing to siblings, and ends with cost and error behavior. Every sentence adds distinct value, and no filler or redundancy is present.

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 tool has a rich output schema and annotations covering read-only behavior, the description covers the key context an agent needs: scope, granularity, alternative tools, cost, and a failure mode. No critical information appears missing for correct tool selection and invocation.

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 the input schema already documents cik, fy_to, and fy_from with examples and suggested usage. The description itself adds little parameter-level meaning, but since the schema handles it well, the baseline score 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 clearly states the tool returns annual financial statements for one company, one row per fiscal year, including income statement, balance sheet, cash flow, and ratios. It distinguishes itself from siblings by naming company_facts, compare_to_peers, and screen_companies, so an agent can immediately tell what this tool is for.

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 says to use this tool for a known company's history and directs the agent to company_facts for individual reported values and quarterly periods, compare_to_peers for industry benchmarking, and screen_companies for finding companies by criteria. This is clear when-to-use and when-not-to-use guidance.

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