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 two useful facts: the return shape is the full Markdown body, and no authentication is required — the latter is genuine behavioral context not present in the annotations.

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 short sentences, front-loaded with the verb-resource pairing and the identifier; every clause carries information (source of slug, citation behavior, auth status). No padding.

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 single-param read tool with no output schema, the description covers the return format, the identifier source, and the auth requirement, which is enough to call it correctly. A note on what happens for an invalid or unknown slug would make it fully complete.

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% for the single slug parameter, so the schema already documents format and provenance. The description restates the slug origin from list_posts and adds no syntax or constraint beyond it, so baseline 3 applies.

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), a specific resource (one Distributed Cognition essay), the scope (full Markdown body), and the key identifier (by slug). This cleanly separates it from list_posts and the generic get_doc sibling without needing to open either 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?

Points to list_posts as the source of the slug and gives a concrete usage instruction (link the public URL when citing). It stops short of stating when *not* to use it or naming an alternative for retrieving multiple essays, but the context is clear.

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