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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds value by detailing the response structure: each entry carries report_period, fiscal_period, filing_date, filing_url, accession_number, a quarterly block with revenue/estimated_revenue/revenue_surprise/revenue_surprise_pct, the same for earnings_per_share, year-over-year change fields, and signals with flags like EPS_BEAT. It also notes that ticker is required and the only parameter. This goes beyond the annotations to explain what the agent will receive and how the data is organized. It doesn't mention rate limits or pagination, but for a single-ticker snapshot with an output schema, this is sufficient.

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 well-structured and front-loaded: it starts with the core purpose, then details the response fields, then gives usage guidance. Every sentence adds value. It is appropriately sized for the complexity of the tool, covering the key output structure and the routing rule without unnecessary fluff.

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 one required parameter, a rich output schema, and clear annotations, the description is complete. It explains what the tool returns in detail, names the alternative for forward-looking estimates, and confirms the only parameter. An agent has everything needed to invoke it correctly and interpret the result. The output schema exists, so the description doesn't need to explain return values further.

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% (the only parameter, ticker, is described as 'The ticker symbol.'). The description adds context by stating 'ticker is required and it is the only parameter,' which reinforces the schema. It also implies the ticker identifies the stock whose earnings are returned. Since the schema already covers the parameter fully, the description's additional emphasis on it being the only parameter is helpful but not extensive. Baseline 3 is appropriate, and the explicit statement about it being the only parameter nudges it to 4.

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: 'Reported earnings for one stock, actuals against estimates.' It specifies the resource (earnings for one stock) and the verb (get/report), and distinguishes it from the sibling tool get_financial_analyst_estimates by explicitly noting the difference between actuals and forward-looking estimates. This makes it easy for an agent to select the correct tool.

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 'Use it for what a company actually reported. For forward-looking consensus that has not happened yet use get_financial_analyst_estimates instead.' This provides clear when-to-use and when-not-to-use guidance, naming the alternative tool. This is exactly the kind of routing information an agent needs.

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