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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and scope are covered structurally. The description adds useful context by naming the return payload ('Summary and URL') and the slug-validity precondition, but with an output schema present the return details are largely duplicative, so this sits at a solid baseline rather than above it.

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 short sentences, front-loaded with what is returned, with the prerequisite second. Nothing is wasted, though the description is terse enough that it leaves gaps rather than being optimally structured for a lookup tool.

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?

Output schema exists so return values need not be re-explained, and the required slug prerequisite chain is stated. For a single-parameter read tool this is nearly complete; the only missing element is what happens on an invalid or unknown slug.

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 0% for the single parameter, so the description must carry the load. It does reinforce that the parameter is a slug used for lookup and that it must come from list_guides, which adds meaning about valid values, but it gives no syntax, format, or case-sensitivity guidance.

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+resource: retrieves 'Summary and URL for one guide', with the lookup key ('slug') called out. The word 'one' plus the lookup mechanism cleanly distinguishes it from the sibling list_guides, so an agent can route correctly without opening 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?

Explicitly states the prerequisite and the alternative path: 'Call list_guides first to get valid slugs.' That is clear when-to-use guidance with a named source of valid inputs, though it stops short of stating when NOT to use this tool.

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