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

Annotations already declare readOnlyHint=true and idempotentHint=true; the description adds 'stateless', which aligns with these hints, and enumerates the specific checks performed. This goes beyond annotations by clarifying the scope of the verification without contradicting any annotation.

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 a single, compact sentence that front-loads the action and then lists the check items in a clear list. No fluff or redundancy; every word contributes to the tool's purpose.

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?

The description explains what the tool does and its stateless nature, but it does not mention what the tool returns (e.g., pass/fail, report) or any error conditions. With no output schema and a single parameter, a bit more context about the result would improve completeness, though annotations cover safety aspects.

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 coverage is 100% (the 'workflow' parameter is described as 'One GitHub Actions workflow YAML document.'). The description does not add additional detail about the parameter format or constraints, so it provides no extra value beyond the schema. Baseline 3 is appropriate.

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 action: 'Perform a stateless preliminary safety check of GitHub Actions YAML' and lists specific aspects (dedicated observer job, continue-on-error, dependency isolation, read-only permissions, immutable DiffCI references). It distinguishes this from sibling tools by focusing on verification rather than interpretation or planning.

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 word 'preliminary' implies this is an early-stage check, but it does not explicitly say when to use this tool instead of diffci_validation_plan or diffci_interpret_report, nor does it state exclusions. The usage context is implied rather than explicitly contrasted with alternatives.

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