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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safe/read-only and closed-world nature is covered. The description adds that it returns SVG markup, which is useful, but it says nothing about error handling for invalid source/id or any output-size limits. Adds some value beyond annotations, but not rich behavioral context.

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 tight sentences with zero filler. The primary action and output are front-loaded, and the input-mode note follows immediately.

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 read-only render tool with no output schema, the description tells the agent what it returns (SVG markup) and how to supply input. The only missing piece is error/edge-case behavior, which is minor here.

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?

Schema description coverage is 75%, so most parameters are already documented in the schema. The description adds the semantically important point that 'source' and 'id' are alternative inputs, but it does not mention theme or showPayloads. Baseline 3 is appropriate given the schema does most of the work.

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 gives a specific verb (render), resource (a Volley diagram), and output format (standalone SVG image), which is more than the title alone conveys. It does not, however, differentiate itself from siblings like check_diagram, describe_diagram, or get_diagram that also deal with diagrams.

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 states that you can 'Pass source text or the id of a saved diagram,' which implies the two input modes, but there is no explicit guidance on when to render versus using check_diagram, describe_diagram, or verify_diagram. Usage is implied rather than contrasted with alternatives.

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