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

Annotations only declare readOnly=false, destructive=true, openWorld=false; the description adds real behavior the agent could not infer — the task appears asynchronously once synced, the response echoes the list and account used, and ambiguous list names cause a refusal with a candidate list rather than a silent pick. It does not explain why a creation tool is flagged destructive or whether the sync can be reversed, which is the remaining gap.

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?

Four short sentences with the core action and sync caveat front-loaded and the ambiguity-handling rule last. Nearly every sentence earns its place, though "The answer names the list and the account it used" is close to return-value detail already covered by the output schema.

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 7-parameter create tool with an output schema and annotations, the description covers the operationally risky parts: sync latency and the multi-account list ambiguity. Field-level semantics (due date format, priority scale, ignored `confirm`) are delegated to the schema, which is acceptable, so nothing critical 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 every parameter is already documented, including the "Account/List" format and the account disambiguation. The description restates that format in prose but adds no syntax or default behavior beyond what the schema provides, 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 and resource ("Creates a task in Microsoft To Do") and immediately discloses the underlying mechanism ("via Reminders sync"), which separates it from todoist_create_task, create_reminder and create_omnifocus_task in the sibling list.

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?

Gives a concrete conditional workflow: when the list name exists across several accounts the tool refuses and returns the candidates, so pass `account` or `list` as "Account/List". It lacks an explicit 'use this instead of todoist_create_task/create_reminder when…' statement, so it is clear context without full alternative routing.

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