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

Annotations already declare idempotentHint=true and destructiveHint=true, so the bar is lower. The description adds genuinely useful context beyond them: the merge/partial-update semantics ('Only the fields you pass change') and the underlying operation (POST /shifts/{id}), which tells the agent the request shape. It does not spell out what a destructive overwrite actually damages or any auth/permission requirement, so it falls short of 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 short sentences with zero filler. The operation type is front-loaded, the field list and partial-update rule follow, and the endpoint is appended last — every sentence earns its place.

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 with no output schema, the description covers the field scope, partial-update behavior, and the HTTP route, and the annotations carry the safety profile. It stops short of noting permission requirements or what the response returns, but nothing essential for correct invocation is missing.

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%, so the schema already documents every parameter including format strings for start_time/end_time and the null-opens-a-shift semantics for user_id. The description's field list merely mirrors the schema properties and adds no format or constraint detail, so 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+resource ('change a shift's times, assignee, location, role, break, notes or published state') and even leads with 'WRITE:', which immediately distinguishes it from read siblings like rotacloud_get_shift and rotacloud_list_shifts. An agent can tell this is the update-shift mutation 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?

The 'Only the fields you pass change' phrasing implicitly conveys patch-style usage, but there is no explicit when-to-use guidance or exclusions. Notably, the sibling rotacloud_publish_shifts exists while this tool can also flip published state, and the description never routes the agent between them — a real ambiguity it leaves unresolved.

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