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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior context beyond that: the returned artifact is the full Markdown body, and no authentication is required.

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 core action and resource, with zero filler. Every sentence carries actionable information (what is returned, where the slug comes from, how to cite it, auth requirement).

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-parameter read tool with no output schema, the description covers the essentials: return format (Markdown body), key source, auth requirement, and citation behavior. Nothing needed 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?

With 1 parameter and 100% schema description coverage, the baseline is 3. The description's note that the slug comes 'from `list_posts`' duplicates the schema's own description ('Essay slug, e.g. from `list_posts`'), so it adds no meaning beyond the structured field.

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?

Specific verb ('Fetch') plus precise resource ('full Markdown body of one Distributed Cognition essay by slug'), including the retrieval key and format. It clearly distinguishes itself from the sibling `list_posts`, which is identified as the source of slugs.

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 establishes the workflow prerequisite by pointing to `list_posts` for slugs and gives an output-handling instruction (link the public URL when citing). It does not state explicit when-not-to-use conditions, but the context is clear for a single-purpose fetch tool.

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