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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower. The description still adds useful behavior beyond them: the response is the full markdown body, and the read-before-edit relationship to napkin_docs_update's replace/append semantics.

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, front-loaded with the core action, then the workflow caveat. No filler or restatement of the name.

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 simple id-based read with fully documented schema params and no output schema, the description supplies the needed return-format hint (full markdown body) and the editing workflow context. Nothing an agent needs to invoke it correctly is missing.

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 100% and both params are documented there, including the workspace/token-default nuance, so baseline 3 applies. The description only reinforces docId provenance ('from napkin_docs_list') and adds nothing about the workspace 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 (fetch), resource (one Napkin doc), scope (full markdown body) and the lookup key (id). This clearly separates it from napkin_docs_list (enumerates) and napkin_docs_update (mutates), so an agent can select it without inspecting siblings.

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 workflow condition — 'Read before editing' — and names napkin_docs_update as the reason, plus points to napkin_docs_list as the id source. It stops short of stating any exclusion or fallback case, so it is strong context rather than full when/when-not routing.

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