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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds useful substance beyond that: the breakdowns returned (adoption rate, YoY growth, first-mention dates) and multi-keyword/ticker capabilities, though it does not discuss limits like result caps or rate behavior.

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?

Front-loads the core purpose before details, and the example queries are informative rather than filler. Slightly long, but each sentence (capabilities, examples, filtering support) carries routing value.

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 an output schema covering return values and annotations covering safety/behavior, the description's job is scoping and routing, both of which it does thoroughly. Nothing needed to invoke it correctly 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?

Schema coverage is 100%, so the schema already documents ticker, keyword, and keywords (including the max-5 rule). The description only restates 'multi-keyword comparison and ticker-specific filtering' without adding format or precedence detail beyond the schema, so baseline 3 is correct.

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 (Search) and resource (keyword/phrase across NZX company announcements) plus the distinctive output (appearance frequency over time by year, sector, company). This temporal-trend framing clearly separates it from raw-search siblings like search_announcements.

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?

Provides four concrete example questions that illustrate exactly when to reach for it (when-did-talking-start, sector comparison, company-specific mentions, keyword-vs-keyword). Clear usage context, but no explicit exclusions or named alternative tools such as search_announcements or get_keyword_alerts.

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