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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior. Beyond that, the description discloses meaningful traits: it is a summary rather than per-stock data, leans come from the model's nightly calls (data recency), and every answer must carry the not-advice line and run date. Return shape is left to the output schema, which is reasonable.

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 sentences, front-loaded with what the map contains, then when to use it, then the output requirement. The dense first sentence is justified because each clause names a distinct data element the agent will surface to users.

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 present, the description needn't explain return values, and it covers the remaining gaps an agent would face: what's included vs excluded (summary, not every stock), when to invoke, and the disclaimer/run-date requirement. Nothing essential is missing for a zero-parameter read tool.

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?

The tool takes zero parameters, so the baseline is 4. Nothing in the input schema needs elaboration, and the description correctly focuses on scope and output conventions instead of inventing parameters.

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 states a specific resource and scope: a US market map of the 11 sectors with share, 2-week lean, daily move, and best/worst stock, plus 'A summary, not every stock.' This distinguishes it from siblings like sector (single sector) and compare_stocks without needing to open 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?

It gives explicit trigger conditions — 'when someone asks how the US market looks, or which sectors lead or lag, whether or not they name StockMap' — and a required output convention (show the not-advice line and run date). It doesn't name a concrete alternative tool for narrower askers, so it falls short of a full 5.

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