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

Annotations only say readOnlyHint=false and destructiveHint=true; the description adds substantially more: idempotency, the completion-time stamp, the returned percentage, the ownership constraint, and the full confirmation handshake (status='confirmation_required', action_id, plan_token). That is exactly the behavioral context an agent needs before attempting a write.

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?

Front-loaded with the core action and its side effects, then a clearly labeled CONFIRMATION block for the workflow rule. Dense but every sentence carries information; minor redundancy between 'idempotent' and the confirmation explanation is tolerable.

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 one-parameter mutation with no output schema, the description covers side effects, return value, ownership scope, and the confirmation protocol. The only meaningful gap is the milestone_id format and provenance, which the description should have supplied given 0% schema coverage.

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% and the single parameter is only typed as integer-or-string with no description. The description never explains what a milestone_id is, where to obtain it, or which form (numeric vs string) is expected. The one parameter that matters most is left for the agent to guess.

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 ('Mark one of the caller's milestones as done') plus the side effect ('stamps the completion time') and the return value (updated completion percentage). It also scopes reachability to 'the caller's own milestone.' It does not explicitly contrast itself with update_milestone or add_milestone, so it falls short of full sibling differentiation.

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?

Clear about when to use it and, importably, describes the mandatory two-step flow, telling the agent that the call is only a proposal and that the write requires confirm_action with the returned action_id and plan_token. It also states an exclusion ('Only the caller's own milestone is reachable'). No guidance on when to prefer update_milestone instead, but the usage path is otherwise unambiguous.

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