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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real value beyond them: it discloses the hierarchical shape of the result and the id-mapping contract (item refId → entity id, e.g. a SHEET item's refId is the sheetId for sheet.schema). It does not mention any size/pagination limits, which matters for a full-workspace tree, so it stops short of a 5.

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 tight sentences, front-loaded with the scope, then the primary use case, then the refId contract, then the alternative. No filler or restatement of the title.

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?

The tool is a simple single-optional-parameter read with an output schema, so return-value documentation is not needed; the description nonetheless supplies the one thing the schema cannot — how refId and spaceId/folderId feed downstream create and read tools. An agent has everything required to call it correctly and route the results.

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% and the single spaceId parameter is already documented ('Return only this space. Omit for every space you can see'). The description reinforces the meaning of spaceId/folderId as targets for create tools, but that is about outputs and routing rather than adding syntax or format detail to the input parameter, 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 with full scope: 'List the spaces the user can see, each with its folders and the items inside them (sheets, pages, dashboards)'. An agent immediately knows this returns a nested hierarchy, not a flat list, and can distinguish it from workspace.search or space.create without opening a 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?

Gives an explicit trigger ('Call this FIRST when you need to create something and must decide where it goes') and names the alternative with the condition that selects it ('Use workspace.search instead when you know the name of the thing you want and just need its id'). Both when-to-use and when-not-to-use are covered.

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