telys_build_lexical

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

Annotations already establish the safety profile (write, idempotent, non-destructive), and the description adds consistent behavioral context beyond them: the index is persisted, the build requires an existing lexical collection, and it 'Fails when the collection does not exist.' No contradiction with annotations — it supplements them with workflow state and failure modes.

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?

Four purposeful sentences: action+precondition, sibling differentiation, workflow ordering, and parameter/failure summary. Nothing is wasted, though the parameter recap partially duplicates the schema; it remains tight and front-loaded with the core action.

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 reasonably omits return values, and it fully covers prerequisites, workflow ordering, parameters, and failure mode. The only gap is behavior when the index already exists, but the idempotentHint=true annotation covers re-invocation safety.

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?

Schema coverage is 100%, so the schema already documents collection, k1, and b with defaults and semantic descriptions. The description restates k1 as 'term-frequency saturation' and b as 'document-length normalization,' mirroring the schema rather than adding new meaning, so the baseline-3 applies.

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 opens with a concrete verb-resource pair — 'Fit the BM25 lexical index over the collection's retained tokens and persist it' — clearly stating what the tool does. It explicitly contrasts with telys_build_ivf, making the distinction from its closest sibling unambiguous.

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?

It names the direct alternative (telys_build_ivf builds the IVF vector index) and states the exact operational window: 'Run after bulk ingestion and before telys_search_lexical.' The precondition that the collection 'must have been created with lexical=True' further pinpoints when the tool is valid, leaving no inference to the agent.

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