Validate diagram code

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

Annotations already mark the tool as readOnly, idempotent, and non-destructive; the description reinforces this with 'without writing any file' and adds the useful behavioral detail that diagnostics include line numbers. It doesn't contradict the annotations and adds meaningful context beyond the structured hints.

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?

A single front-loaded sentence states the core behavior and side-effect profile with no filler. Every part carries information: parse, report errors/warnings, line numbers, no file write.

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 one-parameter, read-only validation tool with annotations covering safety, the description is nearly complete: purpose, diagnostic behavior, and side-effect profile are all present. It loses a point because there is no output schema and the description does not specify the exact diagnostic return shape or how success with no errors is represented.

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 only parameter 'code' is fully documented in the schema, including a pointer to diagram_syntax for language reference. The tool description itself adds no parameter-level detail, so the baseline of 3 applies.

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 ('parse') and resource ('diagram code'), and clearly states the outcome: report errors and warnings with line numbers. This distinguishes it from siblings render_diagram and preview_diagram by focusing on validation, and from diagram_syntax by being an operation rather than a reference.

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 intended use is implied by the name and description: use it to check diagram code for errors and warnings. However, it never explicitly says when to choose validate_diagram over render_diagram or preview_diagram, and the only alternative mentioned in the schema ('Call diagram_syntax') is a language reference, not a validation alternative.

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