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

Annotations already declare read-only, non-destructive, closed-world, so the safety bar is low; the description still earns credit by disclosing that counts are scoped to pages visible to this token (a real permission-dependent behavior) and that ordering is by usage descending. It omits any cap on the number of labels returned, which is the main remaining behavioral unknown.

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 tight sentences plus a parenthetical; every clause carries information (order, scope, service-flag semantics, follow-up tool) with no filler. It is front-loaded on the resource, though the leading noun phrase is slightly less scannable than a verb-first opening.

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 one-parameter read tool with no output schema, the description covers the return shape (labels plus per-label counts, sorted), the scoping rule, and the natural next call. Only the absence of any mention of result-size limits or empty-space behavior keeps it from full completeness.

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?

Single parameter with 100% schema description coverage, so the schema already explains spaceKey. The description reinforces that the listing is confined to one space but adds no syntax or format detail beyond the schema's 'e.g. PM' example. 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 the exact resource (labels of one wiki space), what each entry carries (page counts), the ordering (most used first), and the visibility scope (pages visible to this token). The closing pointer to search_wiki delineates it from the tool that reads a label's pages, so it is unmistakable next to the many wiki siblings.

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?

It routes the agent forward explicitly: 'search_wiki with `label` lists a label's pages,' which clarifies this is the discovery step and search_wiki the consumption step. It also flags the `service` marker so the agent knows how to interpret non-descriptive labels. It stops short of naming when not to use it (e.g. vs. list_wiki_spaces), so not a 5.

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