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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: the exact contents of the concise view (what it does, inputs/outputs, usage, files/links, and for AI tools price, limits and last-checked date) and what detailed adds. It also instructs citing the url, which is a behavioral expectation the annotations don't convey.

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?

Purpose is front-loaded in the first clause and the second sentence covers output modes efficiently. The parenthetical '(skills and workflows work too)' and the long kind enumeration partly duplicate the schema enum, which is mild redundancy but not disruptive.

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?

An output schema exists, so return values needn't be explained, and the description appropriately focuses on which fields the concise view surfaces and what detailed unlocks. Combined with the id-source linkage, an agent has enough to call this correctly; only the revision pinning parameter lacks narrative explanation.

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 enum parameters are already documented in the schema, including the conditional note on 'type'. The description restates the concise/detailed distinction and adds the 'use it only for an item you will run' heuristic, but says nothing about 'revision_sha256' beyond what the schema provides, so the 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 and resource — 'Get one item of any kind by the id from search_library' — and enumerates exactly which item kinds it covers (agent, prompt, mind, AI tool, mini tool, skill, workflow). This makes clear it is the retrieval counterpart to the search_library discovery tool, so an agent can place it immediately.

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 phrase 'by the id from search_library' establishes the prerequisite workflow (search first, then fetch by id), and 'use it only for an item you will run' gives explicit guidance on when the expensive detailed mode is appropriate. It stops short of naming when to prefer a sibling retrieval tool, 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.