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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety burden is light. The description still adds real behavior beyond them: the breadth of the metric universe (87+), the taxonomy of presets, and the filter expression syntax, which tell the agent what classes of query are answerable.

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 front-loaded sentences: capability, supported modes, then example intents. No filler and nothing buried — the screening use cases arrive last, which is the right order for a discovery tool.

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?

For a read-only filtered-list tool with full schema coverage, an output schema, and explicit annotations, nothing an agent needs to invoke it correctly is missing. Return shape is handled by the output schema, so the description is complete without describing responses.

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% and the schema already enumerates every preset name, the filter format, sort examples, and the limit default/max. The description repeats a filter example ('pe_ratio<15,rsi_14<30') already present in the schema, so it adds little parameter meaning beyond structured fields — baseline 3.

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?

Opens with a specific verb+resource ('Screen NZX stocks') plus scope ('87+ metrics — financials, valuation, technical signals, governance, insider activity'), which is far more informative than the generic per-metric siblings like get_technical_signals or get_metrics. An agent can distinguish this as the multi-metric screening entry point without reading the schema.

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?

Explicitly routes screening-type questions ('show me oversold stocks', 'value stocks with high dividends') to this tool, giving clear usage context. It does not name an alternative to use instead when a single-company lookup is wanted (e.g. get_company_detail / search_companies), so exclusion guidance is implied rather than stated.

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