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

The description discloses critical behavioral traits beyond the schema: the hard limit of 9 nodes, the instruction to never send colors/coordinates/SVG (server handles layout/styling), and the return format ('a single line with the page URL - reply with that line only'). These are not present in the annotations (none provided) and are essential for correct usage.

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 compact yet dense with actionable information. Every sentence earns its place: purpose, use case, limit, request formatting, and response handling. It avoids filler and front-loads the most critical information within the first two sentences.

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 nested object schema and the absence of output schema/annotations, the description is remarkably complete. It explains the return value ('single line with the page URL'), usage context, and constraints (node limit, no styling). The sibling tools are 'view_plan' and 'view_report', and the description clearly delineates this tool's niche, leaving no major gaps for the agent.

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 schema already has 100% coverage in parameter descriptions, so the baseline is 3. The description adds value by summarizing the key constraint ('Hard limit of 9 nodes') and the anti-pattern for visual properties, which is not fully covered in the schema properties but is mentioned in the nested diagram description. It doesn't repeat every field, but reinforces the most load-bearing semantic rules.

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 specific verbs and resources: 'Draw a diagram on a local web page' immediately states the action and output medium. It further clarifies the tool's scope by explicitly saying 'without a plan or a report attached', which distinguishes it from sibling tools (view_plan, view_report). The purpose is unmistakable.

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 explicitly tells when to use this tool ('when the user asks how something works and the answer is a picture'), and provides clear exclusion criteria ('without a plan or a report attached'). It also names the alternatives implicitly by contrasting with plans/reports, and gives explicit guidance for splitting complex subjects into multiple calls.

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