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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive, closed-world write. The description adds real behavioral context beyond that: the draft-set state requirement and the hard refusal once milestones are approved, which is exactly the kind of state gating an agent cannot infer from annotations. It omits auth/permission requirements and what happens to an existing set's other data, keeping it from 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?

Two sentences, front-loaded with the action and payload, followed by the gating rule. Every clause carries information; no filler or restatement of the name.

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?

An output schema exists, so return values need not be explained, and the description covers the critical workflow gate that governs success/failure. The remaining gap is the undocumented milestoneSetId parameter and its relationship to open_milestone_set/list_milestone_sets.

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 0%, so the description must carry the parameter burden. It names and explains two of the three parameters (title, definition) but never mentions milestoneSetId or the maxLength/minLength constraints, so it only marginally compensates for the coverage gap.

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 ("Add one milestone") plus the scope ("to a draft set") and the payload (title and definition). An agent can distinguish it from suggest_milestone_change or accept_milestone_change without opening any schema.

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?

Gives an explicit when-not rule: after milestones are approved a new milestone is refused, and the alternative is accept_milestone_change applying an add_milestone suggestion. It does not, however, contrast against suggest_milestone_change for the unapproved-case workflow, so routing in the normal case is left partly implicit.

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