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

With readOnlyHint already declaring a safe read operation, the description adds useful behavioral context beyond annotations: it documents the entry rule and the refusal convention, including that unknown names are refused before payment and returned with accepted names. It does not state whether lexicon_spec itself is free or paid, but the refusal behavior is a meaningful disclosure.

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 one dense sentence with semicolons and nested parentheticals, packing many concepts without clear visual structure. It is front-loaded with the lexicon identity and contains no irrelevant filler, but the run-on structure makes it harder to scan than a few shorter, purpose-built sentences would be.

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?

Given zero parameters, an output schema, and readOnlyHint annotations, the description supplies the key content overview, the paid alternatives, the entry rule, and the refusal behavior. It does not mention the sibling lexicon_statement or state whether this spec call is free, but those are minor gaps relative to the otherwise complete coverage.

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 accepts zero parameters and schema coverage is 100%, so there are no parameter semantics for the description to clarify. Baseline 4 applies because the schema is effectively complete and the description needs no additional parameter detail.

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 resource and enumerates its contents: accepted argument names, their representation and unit, version, bundle hash, namespaces, counts, entry rule, and refusal convention. It also explicitly distinguishes the free spec from the paid meaning-bearing siblings (lexicon_resolve, lexicon_bulk, lexicon_bundle), so an agent can tell what this tool does versus those alternatives.

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 makes clear that meanings belong to the paid lexicon_resolve, lexicon_bulk, and lexicon_bundle tools, implying that lexicon_spec is for names, units, and metadata rather than semantic resolution. It does not explicitly say when to choose lexicon_spec over lexicon_statement or give a formal when-not rule, but the primary alternative is named and the context is clear.

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