set_issue_milestone

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

Annotations already indicate a non-read-only, idempotent, non-destructive mutation. The description adds valuable behavioral context by explaining why clearing a milestone requires null and why update_issue cannot handle that case. This is useful beyond what the annotations convey.

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?

Two focused sentences: the first states the core action, the second explains the rationale for the tool's existence. No wasted words.

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 mutating tool with an output schema and clear annotations, the description fully covers purpose, the clearing edge case, and the reason to prefer this tool over update_issue. Required repo and issue identifiers are self-explanatory and visible in the schema.

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 only 25%, with only the milestone parameter documented there. The description clarifies that milestone can be set or cleared, but it does not explain repo_owner, repo_name, or issue_number beyond their names, and the schema already documents the null-to-clear behavior for milestone.

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 concrete verb-resource pair ('Files an issue under a milestone') and covers the inverse operation ('or takes it off one'). Explicitly distinguishes itself from update_issue by explaining why a separate tool is needed, so an agent can tell it apart from sibling tools.

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?

Names update_issue as the alternative and explains the null-dropping behavior that makes set_issue_milestone necessary for clearing a milestone. This gives clear, concrete guidance on when to use this tool instead of a closely related sibling.

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