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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the write/overwrite risk profile is covered. The description adds a genuine constraint (no deletion path) but omits update semantics that matter for a destructive tool — whether omitted fields are left unchanged, whether tags replace or append, and any permission requirements.

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 short sentences, capability first and the exclusion second, both front-loaded with no filler. There is slight redundancy in re-listing fields that the schema already enumerates, which keeps it just short of ideal.

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 9-parameter mutation tool with full schema coverage, no output schema, and annotations covering the safety profile, the description is nearly sufficient. The missing piece is partial-update semantics and required-permission context, which an agent would want before issuing a destructiveHint=true call.

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 100% and includes richer detail than the description (status alias normalization to Open/Complete, ULID formats, tags replacement, owner resolution). The description only restates the field list, adding no parameter meaning beyond the schema, so the baseline 3 applies.

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 (Update) plus resource (milestone) and enumerates the mutable surface — title, description, dates, tags, status. It does not name or contrast with sibling tools (tm_get_milestone, tm_create_milestone, tm_update_project), so an agent must rely on the tool name alone to disambiguate.

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 one useful boundary — 'Deleting milestones is not available through this connection' — which rules out an adjacent intent, and the status example implies a reopen/complete workflow. However, there is no guidance on when to prefer this over tm_update_project or how to discover the milestone_id (via tm_list_projects/tm_get_milestone) first.

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