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

Annotations only declare readOnlyHint=false and destructiveHint=false, so the description usefully goes further: 'follow-up-pr' opens a new PR while 'append-commit' commits onto the head branch, which tells the agent exactly what side effects each mode produces. It also discloses the required 'repo' scope. It stops short of saying whether generated tests are committed atomically, what happens on failure, or cost implications of an AI call.

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 action and scope requirement. The internal source path reference is the one sentence fragment that does not earn its place for an agent invoking the tool.

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?

No output schema exists, yet the description explains what each mode produces (a new PR vs. a commit on the head branch), which is the key return-behavior information. Combined with the scope prerequisite and annotations covering the safety profile, an agent has enough to call this mutation tool 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 coverage is 50%: 'mode' and 'number' are described, while 'owner' and 'repo' are bare. The description adds genuine meaning to the mode values by explaining their outcomes, compensating for the schema's terse enum-like listing, but it adds nothing for the two undocumented parameters. Baseline 3 is appropriate given partial coverage and partial compensation.

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?

States a specific verb and resource ('Generate tests for a PR') and clearly differentiates from siblings like merjax_generate_commit_message and merjax_generate_pr_description. The mention of the internal module ('Wraps src/lib/ai-test-generator.generateTestsForPr') adds no distinguishing value for an agent choosing a tool, but it doesn't obscure the purpose.

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 implies usage by naming the two modes and their divergent behavior, plus a 'requires repo scope' prerequisite, but it never states when to choose this tool over alternatives (e.g., a plain PR review) or when the modes are inappropriate. An agent must infer selection rules from the mode names alone.

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