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

The description discloses the mutation behavior and the required write scope, adding useful safety context beyond the empty annotations. It does not detail side effects, partial update semantics, or return values, but the auth requirement helps.

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 one sentence with clear front-loading of the purpose, followed by the auth requirement. Every word adds value, and there is no redundancy.

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 update tool with five well-documented parameters and a single required ID, the description plus schema covers the essential aspects. It notes the required scope and updatable fields, though it does not describe the return value; given no output schema, this is a minor gap.

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 with detailed descriptions for all five parameters, including guidance for assign_to. The tool description only repeats field names without adding new semantic detail, so it meets the baseline of 3.

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 clearly states 'Updates an existing action item' with a specific verb and resource, and enumerates the mutable fields (text, priority, due date, assignee), distinguishing it from sibling tools like create, complete, and 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?

It provides clear context ('existing action item') and a prerequisite ('Requires mcp:write scope'), which tells the agent when it is appropriate to call. However, it does not explicitly name alternative tools or state when not to use it.

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