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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered; the description's own "Read-only" line is redundant. However, it adds two genuinely new behavioral facts: scope is per-caller rather than global, and the sentinel value -1 means unlimited, which is essential to interpreting the output correctly.

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?

A single front-loaded sentence delivers the full field list, followed by two short clauses for the read-only guarantee and the -1 sentinel. No filler, and the most important information (what is returned) comes first.

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?

With no output schema, the description carries the burden of describing return values, and it does so by enumerating the three reported metrics and their limit counterparts plus sentinel semantics. Only minor gaps remain, such as units or formatting for bytes and whether limits are per-plan or per-collection.

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 the baseline is 4 and there is nothing for the description to disambiguate. No parameter-level detail is possible or missing.

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 names a specific verb and resource ("Report the caller's KB usage vs plan limits") and enumerates exactly what is reported: storage bytes, chunk count, and collection count against their limits. This is clearly distinct from the sibling tools, which are ingest/create/delete/list operations rather than a quota read.

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?

There is no explicit when-to-use statement — for example, 'call before kb_ingest_document to check remaining capacity' — nor any exclusion of alternatives. The framing ('vs plan limits') implies a pre-flight quota check, so usage is inferable but never stated.

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