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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine value beyond them by disclosing what comes back per collection (document and chunk counts), which is important given there is no output schema. 'Read-only' restates the annotation, but the return-content disclosure earns the higher score.

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, zero waste, with the resource and scope front-loaded and the return content immediately after. Nothing redundant beyond the minor restatement of read-only status.

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 zero-parameter list tool with no output schema, the description covers purpose, scope and return contents. Minor gaps remain: ordering of results, behavior on an empty knowledge base, and any pagination or result cap are unstated, though these are unlikely to change an invocation decision.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a parameterless tool is 4. The schema is closed (additionalProperties=false) and empty, consistent with the description.

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?

The description states a specific verb ('List') and resource ('knowledge-base collections') and scopes it to 'the caller's', so an agent knows exactly what it returns. It does not explicitly name a contrasting sibling (e.g. kb_search or kb_create_collection), which keeps it just short of a 5.

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?

Usage is only implied: the tool enumerates collections, which an agent would reasonably call before creating, ingesting into, or deleting a collection. There is no explicit 'use this when...' or exclusion of alternatives such as kb_search, so the guidance is adequate but inferred.

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