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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is largely covered. The description adds the genuinely useful partial-update contract ("Only specified fields will be updated"), but says nothing about what destructive means in practice — e.g. that passing assignees replaces the existing list wholesale — or about permissions/irreversibility.

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, zero padding, and the scope rule is front-loaded ahead of the partial-update caveat. Nothing repeated and nothing wasted.

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 and annotations carry the risk profile, so much is covered structurally. However, for a destructive 8-parameter mutation the description never states that omitted fields are preserved while provided ones (notably assignees) are overwritten, nor any failure/permission conditions — gaps an agent would want closed.

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 the schema already documents due-date formats, assignee replacement and projectId scoping in detail. The description adds no parameter-level meaning beyond restating the projectId rule, 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?

Names a specific verb and resource ("Update an existing task") plus the scope rule that distinguishes personal from project tasks. It does not explicitly contrast with siblings like xtiles_delete_tasks or xtiles_get_task, so sibling differentiation is left implicit.

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 projectId/omit rule gives a conditional, but this is really parameter scoping rather than when-to-use guidance. There is no mention of prerequisites (e.g. fetching the task first) or of which sibling handles deletion/creation instead.

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