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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds useful mechanism context (hybrid retrieval pipeline) but says nothing about ranking behavior, relevance scoring, or result ordering that an agent might need to interpret output.

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?

Three short sentences, front-loaded with the core purpose, no repetition or filler. "Cohere reranking" is slightly vendor-specific trivia but does convey ranking quality information, so it earns its place reasonably.

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?

The output schema exists, so return-value explanation is correctly omitted, and annotations cover safety. The main missing piece is sibling differentiation against search_announcements and other search tools, which is material given the large, overlapping sibling set.

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%, with all six parameters including q, from/to, type, limit, and ticker documented in the schema itself. The description adds no parameter-level detail beyond what the schema provides, so the baseline 3 is appropriate.

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 and resource ("hybrid semantic + keyword search across NZX announcements") and explains the mechanism (embeddings, BM25, vector similarity, reranking). It's clear what the tool does, but it never distinguishes itself from the obvious sibling search_announcements, so an agent has no basis for choosing between them from this 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 phrase "even if exact keywords differ" implies when semantic mode is preferable to a keyword search, giving implied usage guidance. But there is no explicit when-to-use/when-not and no reference to alternatives such as search_announcements, leaving the routing decision to inference.

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