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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description is not carrying the safety burden. It still adds real operational context the annotations lack: it reads account history and therefore requires a Smoke Run API key, and it returns an empty result when no check exists for the site. It stops short of describing rate limits or what the findings payload contains beyond 'dollar-proof'.

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 short sentences, front-loaded with the return value and followed by the auth requirement and the empty-state edge case; each sentence carries distinct information. 'Reads an account history, so it needs a Smoke Run API key' is slightly indirect phrasing for the auth requirement but remains efficient.

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 one-parameter read tool with annotations present and no output schema, the description covers what is returned, the auth prerequisite, and the no-data case, which is enough for correct invocation. The remaining gap is the shape of the findings payload, which the agent only learns at call time.

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 siteUrl is already documented with type, format example, and length bound; baseline 3 applies. The description reinforces that the parameter selects a single site's history but adds no syntax, normalization, or validation detail beyond the schema.

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 names a specific verb and resource (returns the most recent revenue-path check) plus the scope (for a given site) and the payload (dollar-proof findings). It implicitly distinguishes itself from list_checks and run_revenue_check by emphasizing 'most recent' and 'read', but it never names those siblings, so an agent must infer the boundary.

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: 'most recent' suggests retrieval of existing results rather than triggering a new check, which points away from run_revenue_check, and the single-site scope points away from list_checks. There is no explicit when-to-use, when-not-to-use, or named alternative, and no prerequisite ordering (e.g., run a check first) beyond the empty-result note.

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