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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this mutates state. The description adds valuable patch-behavior context (unpassed fields are preserved, clearDueDate removes the date) that the annotations do not convey. It stops short of explaining what destruction means here or what identifiers/authorization the call requires, so it neither contradicts nor fully enriches the annotation profile.

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, front-loaded with the field list and zero filler. Every sentence carries information the agent needs: what changes, that it's a partial update, and how to clear a due date.

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 an 8-parameter mutation tool with 13% schema coverage and no output schema, the description covers the mutation semantics well but omits how to identify the target (listId, taskId), whether it requires mailbox authorization, and what happens on invalid IDs. Adequate but with clear gaps.

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 only 13% (just 'mailbox'), so the description must compensate: it explains clearDueDate and the omit-vs-explicit dueDate distinction, which is genuinely beyond the bare schema. However listId and taskId — two of three required parameters — get no explanation anywhere, so coverage is still incomplete. Baseline 3 fits given the partial compensation.

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 ('Change a task's title, notes, due date or status') and enumerates the mutable fields, so the agent knows exactly what this tool does. It does not differentiate itself from near-siblings like update_outlook_task or complete_google_task, which is the only thing keeping it from a 5.

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 description gives useful invocation semantics ('only the fields you pass are touched', 'clearDueDate to remove a due date'), which is real guidance on how to call it. It never says when to pick this over alternatives such as update_outlook_task or complete_google_task, nor any prerequisites, so usage guidance is implied rather than explicit.

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