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

Beyond annotations (readOnlyHint, openWorldHint, idempotentHint), the description adds significant behavioral context: it truncates the topic tail, stays short enough to read in full, ranks the busiest first, and states structure rather than signal content. This is more than the annotations convey, though it doesn't detail error cases or exact response formatting.

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 description is well-structured and front-loaded: it states the core purpose first, then usage guidance, then the key distinction from list_facets. Each sentence earns its place; even the final sentence adds the crucial caveat that the manifest is about structure, not content. No fluff or repetition.

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, read-only tool with no output schema, the description is unusually complete. It covers what the output is, how it's ranked, how it is truncated, why it should be used, where it fits in the workflow, and when to use the sibling list_facets. No essential decision-making context is missing.

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 has zero parameters, and the schema already reflects 100% coverage, so parameter explanation is unnecessary. The description does clarify what the output covers ('two facet keys only, domain and topic'), which indirectly explains the absence of filter parameters. With no params, the baseline is 4 and there is no deficiency.

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 uses a specific verb and object—'Read the shape of the wire'—and explains exactly what is returned: a two-level tree of domain and topics with signal counts, ranked by busiest. It clearly distinguishes itself from siblings like list_facets by saying it covers only domain and topic, and from scope_signals/search_signals by framing itself as the map to read first.

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?

The description gives explicit guidance: read the manifest once, choose a scope offline, then make one precise call to scope_signals or search_signals instead of guessing a filter. It also says when to call list_facets instead—when exhaustive vocabulary is needed. This is strong when-to-use versus when-not-to-use guidance.

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