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

Annotations already establish that this is a mutating, non-destructive, non-idempotent operation, and the description does not contradict them. It adds the semantic that the TODO is 'marked completed' and points to list_memory_todos for the ID, but it does not disclose side effects such as whether completed TODOs vanish from active lists, whether repeated completion errors, or whether the action is reversible. The added context is useful but not rich.

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?

The description is a single well-structured sentence that packs the operation, trigger, and cross-reference without wasted words. It is front-loaded with the verb and resource, making it immediately scannable.

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 simple two-parameter mutation with an output schema and reasonable annotations, the description covers the core purpose, trigger, and ID sourcing. It lacks explicit mention of post-completion state or alternatives, but those gaps are minor and the overall package is sufficient for an agent to select and invoke the tool correctly.

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?

The input schema already provides 100% coverage for both parameters (todo_id and note), so the baseline is 3. The description adds value by explaining that the todo_id is the exact memory reference shown by list_memory_todos, which helps the agent correctly obtain the ID before calling the tool.

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 uses a specific verb ('Marks'), identifies the exact resource ('a TODO/action item'), and includes the user trigger ('when the user says a saved task is done, resolved, or no longer needed'). It clearly distinguishes this from sibling tools like create_memory_todo and list_memory_todos by focusing on the completion action.

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 explicitly states when to use the tool ('when the user says a saved task is done, resolved, or no longer needed') and references list_memory_todos as the source for the exact memory reference, implying a look-then-complete workflow. It does not explicitly exclude alternatives like update_project_todo, but the narrow purpose makes the intended usage clear.

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