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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description correctly doesn't repeat that. It adds behavioral detail beyond those annotations: the return format (one row per ticker, latest-restated value, separate listing for tickers with no data) and the fiscal calendar alignment caveat. This enriches the agent's understanding of the tool's output 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 two concise sentences: the first states the primary purpose and return behavior, the second provides a critical caveat about fiscal calendar variation. Every sentence earns its place, with the main purpose front-loaded and no wasted words.

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 read-only comparison tool with no output schema, the description adequately covers key operational details: the return row structure, treatment of missing data, and the fiscal calendar nuance. It even directs the agent to check the Period End column, which implies that column exists. This is sufficient for an agent to call the tool correctly and interpret results.

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?

The schema covers all parameters with descriptions (100% coverage), so the baseline is 3. The description adds extra meaning by highlighting that fiscalYear/period refer to each company's own fiscal calendar, which is not explicitly stated in the schema descriptions but is crucial for interpreting results. This goes beyond the schema to clarify a potential source of confusion.

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's purpose: comparing a single financial concept across multiple companies for a given fiscal period, explicitly calling it 'peer comparison'. It also specifies the return structure ('one row per ticker...') and distinguishes itself from single-company tools like GetFinancialFact by its multi-company focus.

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 provides important usage context, notably that fiscal years follow each company's own calendar and that peer rows can cover different months, urging the agent to check the Period End column. However, it does not explicitly name alternative tools or specify when not to use it, though the peer-comparison purpose implies the appropriate context.

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