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

Annotations already declare destructiveHint=true and non-idempotent, but the description goes beyond them by disclosing a lifecycle gate: new milestones are refused post-approval until a suggestion is applied. It does not explain what makes the write destructive or whether repeated calls create duplicates, so the disclosure is strong but not exhaustive.

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, zero filler, with the core action front-loaded and the lifecycle constraint following immediately. Every clause carries information an agent needs.

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 no explanation, and the state-machine behavior is well covered. The remaining gaps are the undocumented milestoneSetId and how a set reaches draft status, which are minor for a three-parameter add 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 0%, so the description must compensate. It names two of the three parameters ('a title and the definition of that milestone'), clarifying the semantic split between title and definition, but it never mentions milestoneSetId or the length constraints, leaving the call-shaping parameter undocumented.

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 specific verb and resource ('Add one milestone to a draft set') and immediately scopes it to draft sets, which cleanly separates it from approve_milestones and accept_milestone_change in the sibling list. An agent can identify the operation and its target state without opening the 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?

It states the condition under which the call succeeds (a draft set), the condition under which it is refused (after milestones are approved), and the remediation path (accept_milestone_change applying an add_milestone suggestion). When-to-use, when-not-to-use, and the alternative route are all explicit rather than inferred.

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