rerank

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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description adds genuinely useful behavioral context: the operation is deterministic, failure occurs with invalid_embedding_dimensions when dimensions differ, and the response includes rank starting at 1, score, total_documents, and returned_documents counts.

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 compact and front-loaded: purpose first, then the prerequisite, then the failure condition, then return shape. Every sentence earns its place, and there is no repetition of schema content.

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?

Despite having no output schema, the description explains return values, the failure mode, and the prerequisite workflow. For a 4-parameter tool with full schema coverage, this is complete enough for an agent to invoke it correctly without additional context.

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 description coverage is 100%, so the baseline of 3 applies. The description reinforces the relationship between query_embedding and documents (shared dimension) and mentions the default metric, but it does not need to add much because the schema already documents all four parameters thoroughly.

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 specific verb ('Rank') and a precise resource ('caller-supplied document embeddings against a query embedding'), making the tool's function immediately clear. It also differentiates itself from the sibling 'embeddings' tool by explicitly stating it does not embed text.

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 clear when-to-use guidance by instructing the caller to invoke 'embeddings first' to produce vectors, and it warns about the dimension-matching prerequisite. It does not explicitly name alternative ranking/similarity siblings like embedding_similarity or score, so exclusion guidance is slightly implicit, but the primary workflow is well defined.

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