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

Annotations only supply the generic safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false); the description adds genuinely behavioral context: a license requirement, a two-phase preview-then-confirm gate, and the ambiguity that a matching task_name completes only the first match found. It also states what is returned, which is more than the annotations carry.

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?

Front-loaded with the action, then prerequisites, then routing guidance. Five compact sentences with little waste; the closing sentence about the return value is marginally redundant given an output schema exists, but it carries rationale (telling the user which task was completed).

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 3-parameter mutation tool with an output schema, the definition covers everything an agent needs: prerequisites, id-vs-name selection, ambiguity behavior, the confirm gate, and what the call returns. Nothing material is left to inference.

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 100%, so the baseline is 3. The description still adds meaning beyond the schema by stating the preference order between task_id and task_name, the exact-match requirement, and the first-match-only consequence of using task_name.

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 ("Marks an OmniFocus task as complete") and implicitly differentiates from the many sibling completion tools (todoist_complete_task, todo_complete_task, complete_reminder) by naming the OmniFocus domain and its list/search siblings. An agent can route to it without opening a 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?

Explicitly tells the agent to prefer task_id sourced from list_omnifocus_tasks or search_omnifocus_tasks, describes the fallback condition (when you don't have the id) and the exact-match/first-found caveat, and gates execution behind confirm=true with a preview otherwise. Prerequisite (OmniFocus Pro) is also stated.

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