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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions the operation is a save (creation), returns id and URL, may trigger a free-plan limit (paywall), and requires an API key. This goes beyond a simple 'Creates a diagram' by providing actionable context about constraints and response.

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?

Three sentences, front-loaded with the core purpose. Every sentence provides unique info: the action, the return value, and the limitations/auth. No filler or 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?

Given the simple nature of a create tool and the rich schema (all params defined, enum provided), the description covers the key points: purpose, authentication, paywall, and return value. It lacks details on error cases (e.g., invalid YAML) but that is often handled by schema validation. The absence of an output schema is mitigated by mentioning the id and URL.

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 describes all three parameters with high coverage (100%), including types, constraints, defaults, and enum values. The description adds no parameter-specific meaning beyond the schema, such as what 'yaml' should contain or what each diagramType means. Baseline 3 is appropriate.

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 states a specific verb and resource: 'Save a new diagram to the user's account.' This clearly differentiates from sibling tools like update_diagram (modifying existing) or get_diagram (retrieving). It also notes the return value (id and URL), clarifying what the tool achieves.

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 creating new diagrams but does not explicitly state when to use this tool versus alternatives like update_diagram or convert_yaml. There are no exclusions or alternative recommendations. The only guidance is the paywall and API key requirements, which are more constraints than usage direction.

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