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

Beyond the readOnly/non-destructive/closed-world annotations, the description discloses the authorization prerequisite ('Requires the invoice:read scope') and warns that the payload is the entire report rather than a scalar summary, which is exactly the kind of expectation-setting the annotations cannot convey. These are concrete operational details an agent needs before calling.

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?

Three tight sentences, front-loaded with the purpose and default behavior, then the sibling comparison, then the scope requirement. No filler or redundancy.

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 compensates by stating what is returned (the full P&L v2 report with the same fields as its sibling) and the required scope. Combined with 100% parameter coverage in the schema, an agent has everything needed to select and invoke it correctly.

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 every parameter (companyId, dateFrom, dateTo, period) is documented in the schema, so the baseline is 3. The description only restates the default window ('current quarter to date'), which largely duplicates the period/dateTo defaults already described in the schema, adding little new parameter meaning.

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?

Names a specific verb and resource ('Get the profit and loss v2 report') and immediately frames it against its closest sibling by stating it calls the same endpoint and returns the same fields as get-profit-and-loss-v2, with only the default dates differing. It also corrects the likely misreading of the name by clarifying it returns the full report, not a single revenue figure.

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?

Gives a clear use context ('for revenue questions', defaulting to current quarter to date) and names the alternative (get-profit-and-loss-v2) with the exact distinction between them. It stops short of an explicit routing rule such as 'use this when the user gives no date range; otherwise use get-profit-and-loss-v2', so the agent must infer which to pick when dates are supplied.

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