Render Diagram

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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=true, openWorldHint=true), and the description adds real context beyond them: the tool both returns an image and writes a server-side file, and that file is what a wiki writer uploads. It doesn't describe how theme/scale/output_format affect the rendered output, so it stops short of full disclosure.

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?

Two sentences, zero filler, with the capability stated first and the sibling differentiation immediately after. Every clause carries information an agent would otherwise have to infer.

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?

An output schema exists, so return values need only partial explanation, and the description handles that. But for a 5-parameter tool with zero schema coverage, the description should at minimum clarify diagram_type values and point to the sibling list_diagram_types; that omission is a real gap for correct invocation.

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?

All 5 parameters have 0% schema description coverage, so the description carries the full burden — yet it says nothing about diagram_type, code, scale, theme, or output_format. It documents the outputs (image, local_path) but no input semantics or valid values for diagram_type, which is a required parameter.

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?

States a specific verb (render) and resource (diagram) plus the concrete deliverables: an MCP image and a server-side file path. It explicitly contrasts itself with the sibling generate_uml, so an agent can distinguish the two without opening either schema.

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?

Gives an explicit selection rule — 'Use this instead of generate_uml when the figure should appear in chat or be uploaded' — naming both the alternative and the condition that picks it. The rationale (no base64 copying, uploadable local_path) removes any ambiguity.

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