Semantic index statistics

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds meaningful context beyond that: it enumerates what is reported (indexed-or-not, cached document count, embedding model + dimensions) and states the empty-summary fallback when no client resolves. It does not contradict any annotation. It could disclose more about the failure surface, but the 'On failure' pointer to tool-schema partly compensates.

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?

The core purpose and return shape are front-loaded and information-dense. The trailing 'Signature / Phase / cost / idempotency / Requires / Produces / Safety / On failure' boilerplate is padded and partly redundant with the annotations, which costs a point on a short description.

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-param read-only observation tool with no output schema, the description covers purpose, scope, return contents, and the empty-result behavior. It does not enumerate the exact output fields, but it points the agent to tool-schema on failure, which is an adequate completeness level.

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?

Zero parameters, so the per-rubric baseline is 4. The description notes it resolves the active client from session selection and documents the no-client fallback, which is the only 'input-like' behavior that matters here.

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 (Report) and resource (semantic script index statistics) and explicitly names the scope ('THIS session's active client WITHOUT touching the game'). This distinguishes it cleanly from siblings like semantic-search-scripts and clear-semantic-index, which operate on the index rather than reporting on it.

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?

Explicitly states when to use it: 'Use it to confirm an index exists before searching, or to see which embeddings backend is active.' This gives the agent both the prerequisite-check use case and the informational use case, and the no-touch framing rules out alternatives for probing index state.

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