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

Annotations already declare destructive=true, idempotent=true, readOnly=false, so the safety profile is covered. The description adds genuinely new behavior: the server-time stamp and the MCP_CONFLICT failure mode when the task changed after expectedUpdatedAt — an optimistic-concurrency contract not visible in structured fields.

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?

Three short sentences, each earning its place: what it does, when to call it, and the failure mode. The core action is front-loaded with no filler.

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 needn't be described, and the conflict/error path is disclosed. The only gap is the idempotencyKey contract, which matters for retry behavior on a non-readOnly tool, though idempotentHint=true partially covers it.

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 effectively explains expectedUpdatedAt via the conflict rule, and projectId/taskId are self-evident, but idempotencyKey is never mentioned (only indirectly covered by idempotentHint). Partial compensation warrants the baseline 3.

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: 'Move one task to the project's completed status, stamped with server time.' The scope (one task, project-level completion, server-timestamped) clearly separates it from the generic siblings clean_notes_update_task and clean_notes_create_task.

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?

'Use when the user says a task is done' gives a concrete trigger condition, which is more than most siblings offer. It does not state when NOT to use it (e.g. for partial edits use update_task), so it stops short of the full routing guidance a 5 requires.

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