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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the non-obvious fallback: on multiple name matches it returns candidate valuations instead of statements. That is exactly the kind of surprise behavior an agent needs warned about. It does not mention units, currency, or behavior when no company matches.

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?

Two sentences, zero filler, with the primary return content front-loaded and the edge-case behavior trailing. Every clause carries information an agent would otherwise have to guess.

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 correctly carries the return shape (statements by year plus derived EBITDA/margins, or a candidate list). For a read tool with full annotation coverage this is nearly sufficient; missing only minor details such as units/currency and the not-found case.

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 coverage is 100% and both parameters are documented, including that 'valuation' selects among several valuations of the same company, so the baseline is 3. The description's 'chosen by company name' and the multi-match note largely restate the schema rather than adding format, precedence, or partial-match semantics beyond it.

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 (returns historical financial statements) and enumerates the returned artifacts: P&L, balance sheet by year, EBITDA, margins. It also discloses the ambiguity branch. It does not explicitly distinguish itself from the sibling get_company_valuation, so an agent must infer that one returns valuation data and this one returns statements.

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 implied rather than stated: the tool is selected by company name, and the 'if several valuations match' sentence tells the agent what happens in the ambiguous case. There is no explicit when-to-use versus get_company_valuation or when to call list_companies first to disambiguate, leaving the routing decision to inference.

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