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

The annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered structurally. The description adds useful behavior the annotations cannot: partial-patch semantics and the fact that setting due_date silently removes an offset deadline (and vice versa), which is exactly the destructive side effect an agent needs to know about. It stops short of saying what the response contains or what happens to omitted fields on failure.

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 tight sentences with zero filler; the field list is front-loaded and the edge-case rule about the two deadline representations follows immediately. Nothing is repeated from the schema or annotations.

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 6-parameter mutation tool with no output schema, the description covers the field set, patch semantics, and the one non-obvious parameter interaction. It would be stronger with a note on the return value or on what a null for other fields means, but the essential calling information is present.

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 coverage is 50%: id, due_date, and offset_days are documented in the schema, while title, notes, and status carry no per-parameter text. The description compensates by listing the mutable fields and, importantly, by explaining the mutual exclusion between due_date and offset_days plus the null-to-remove convention. That is genuine added meaning, but the bare title/notes/status parameters still get nothing beyond their names.

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?

The description names a specific verb and resource and enumerates exactly what can change: status (with its three values), title, notes, and deadline. That is far more informative than 'updates a task'. It doesn't explicitly contrast itself with add-task or delete-task, but the mutation scope is unambiguous.

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?

It states the key partial-update rule ('Only the fields you pass change') and the due_date/offset_days interaction, which is real usage guidance for the trickiest part of the call. It gives no guidance on when to use this versus add-task or delete-task, and no prerequisites or permission context.

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