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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds output composition but does not reveal behavioral nuances like data freshness, market-hours limitations, or failure behavior. It is adequate but not enriched beyond what annotations already provide.

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?

Two focused sentences: the first states the resource and what it returns, the second gives concrete usage triggers. There is no filler and the essential information is front-loaded.

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 tool with one optional parameter, full schema coverage, and an output schema present, the description fully supports selection and invocation. Nothing critical is missing for an agent to decide when to call it.

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% for the single optional 'days' parameter, including minimum, default, and usage guidance ('Use 1 for last trading day, 7 for the week'). The description adds no new parameter semantics, but none are needed because the schema fully documents it.

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 specifies a precise verb and resource: it gets a market-wide NZX digest covering all active issuers, and enumerates contents (price moves, breadth, announcements, insider trades, dividends, board changes, AI summary). This clearly distinguishes it from sibling company-specific tools like get_stock_prices or get_dividends.

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 explicitly gives invocation triggers: 'when asked about overall market conditions, today's market, what happened on the NZX, or market summary.' It does not explicitly mention when not to use it or name alternatives, but the market-wide scope and trigger phrases are clear.

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