check_diagram

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

With no annotations, the description carries the full behavioral burden. It clearly states the tool is non-writing, describes the return structure (status, summary, warnings with hints, boxes/edges), and provides an example of a hint. This is solid disclosure for a read-only validation tool, though it omits potential error conditions or edge cases.

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 three sentences long, front-loaded with the core action and output. The only minor redundancy is 'without writing anything' and 'before rendering', which both emphasize non-mutating behavior. Overall, every sentence earns its place.

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 3-parameter tool with 100% schema coverage and no output schema, the description covers the main purpose, return values, and usage timing. It does not describe error handling or repair specifics, but those are covered by the schema. The description is sufficiently complete for an agent to call the tool correctly.

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 100%, so the baseline is 3. The tool description adds little beyond the schema: it mentions boxes/edges and an example hint, but these are already implied by the schema descriptions. No new parameter meaning is introduced.

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 'Validate' with a clear resource 'ASCII/Unicode box diagram', and explicitly states it does so 'without writing anything', distinguishing it from the sibling render_diagram. The purpose is immediately clear and actionable.

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 says 'Use it to confirm a diagram means what you intended before rendering', which gives a clear contextual trigger. It implies but does not explicitly name render_diagram as the alternative, and offers no 'when not to use' conditions, so it stops short of a full 5.

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