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

With no annotations, the description must disclose side effects. It only mentions the API key requirement, which is useful, but it omits whether the update is partial or full, how omitted fields are handled, and what happens on invalid YAML. This is a significant gap for a mutation tool.

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, focused sentence that states the core operation and a key prerequisite. There is no filler or redundancy, making it appropriately concise and efficient.

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 mutation tool with no annotations and no output schema, the description lacks critical context such as update semantics, response behavior, and error conditions. It provides only the basic operation and auth requirement, which is insufficient for an agent to anticipate consequences.

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 schema covers all four parameters with descriptions at 100% coverage, so the baseline is 3. The description's 'source, title and/or type' adds no new meaning beyond the schema properties, which already explain each field.

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 the action (update), the target resource (existing diagram), and the modifiable attributes (source, title, type). This differentiates it from siblings like create_diagram and delete_diagram, which have distinct purposes.

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 implies usage for modifying existing diagrams but does not explicitly compare with alternatives or state when not to use it. The mention of 'existing diagram' gives context, but there are no direct references to create_diagram or other relevant siblings.

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