Get an error's impact

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

Annotations already declare readOnlyHint=true, so the safety profile is known. The description adds behavioral value by specifying that the tool returns only counts and not named users, detailing the exact output fields. However, it does not disclose additional behavioral traits like pagination or performance, so it falls short of a 5.

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 sentences plus a third for alternative guidance. It is front-loaded with the core action and outputs, with no extraneous information. Every sentence serves a purpose: defining the tool, specifying outputs, and directing to a sibling when needed.

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?

Despite lacking an output schema, the description fully describes the return values (distinct users, paying customer count, error type, status, counts, timestamps). It also specifies the input as a fingerprint from the Crossdeck Errors view and mentions the sibling tool for detailed data. For a tool of this complexity, this is complete.

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%, with each parameter having a detailed description (e.g., project explains required vs. ignored conditions). The tool description only adds 'by fingerprint/issue id' for the fingerprint parameter, which is already implied by the schema description. Hence, the description adds minimal semantic value beyond the schema, warranting a baseline 3.

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 gets blast radius for one error by fingerprint, listing specific outputs (distinct users, paying customers, error metadata). It distinguishes itself from sibling 'get_error_affected_users' by noting that this tool returns only counts, while the sibling provides named users and revenue. This meets the criteria for a specific verb+resource and sibling differentiation.

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 tells when to use this tool ('Use to size an error's impact') and when to use an alternative ('For the NAMED paying users... call get_error_affected_users instead'). This provides clear context and exclusion, which is the top tier of usage guidance.

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