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

Annotations already declare the safety profile (readOnly=false, destructive=false, openWorld=false). The description adds substantial behavioral context beyond that: the output renders as an interactive clickable card, must be cited as [[diagram:ID]] on its own line, and must never be cited as [[board:ID]]. It omits any mention of auth/scoping limits, but the added rendering and citation semantics are genuinely useful.

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?

Three dense sentences, front-loaded with the identity/scope distinction, followed by the input requirement and then output/citation behavior. No filler and no repetition of the title.

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?

No output schema exists, and the description compensates by specifying the citation format the agent must emit. Combined with annotations covering the safety profile and the rich 'source' schema, the definition is near-complete for a create tool; only auth/workspace scoping behavior is left to the schema.

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 coverage is 67%, and the 'source' parameter is already heavily documented in the schema (mermaid syntax, node shapes, subgraphs, styling). The description only restates 'Pass the mermaid source', adding no syntax or constraint detail beyond the schema. Baseline 3 is appropriate.

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+resource ('Create a Napkin diagram — an interactive FLOWCHART') and immediately draws the boundary against the two nearest siblings by name (napkin_docs_create, napkin_boards_create). An agent can route correctly without opening any 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?

Explicitly names the alternatives and what this tool is NOT ('not a doc... or drawing canvas'), then gives the positive trigger condition ('Use for process maps the user asked you to draw'). The mermaid input requirement further constrains selection.

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