create_milestone

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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, which covers mutability and non-idempotence. The description adds a useful failure mode—reusing a title fails on a per-repository basis. No other behavioral traits like authorization or response details are disclosed, but the added constraint gives some context beyond annotations.

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 sentences with zero filler. The key constraint (title uniqueness) is stated directly and the description is appropriately sized for the tool's complexity.

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 output schema exists, so return values need no explanation. Required parameters and the default state are covered by the schema. The major gap is the ambiguous 'Opens' wording, the lack of usage guidance, and the sparse parameter-level detail in the description. The uniqueness note is helpful, but overall the definition is thin for a 6-parameter mutating tool.

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 17%, so the description should compensate heavily. It only adds meaning for 'title' (uniqueness) and weakly hints at 'state' via 'Opens'. The parameters repo_owner, repo_name, description, and due_on receive no semantic explanation beyond the schema's basic type and default information.

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 resource (milestone) and an action ('Opens'), which is clear enough when combined with the tool name create_milestone. The uniqueness note on titles makes the creation intent clear, but 'Opens' could also be misread as changing the state of an existing milestone. It still stands out reasonably from siblings like update_milestone.

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?

No guidance on when to use this tool versus alternatives. The description never mentions update_milestone, set_issue_milestone, or list_milestones, nor does it clarify that this is for creating a new milestone rather than modifying an existing one.

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