get_market_status

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

Annotations already establish that this is a read-only, idempotent, non-destructive, open-world operation. The description adds useful behavior beyond those annotations: accepted region categories, default behavior, the fact that other country codes are rejected, and that an unrecognized region returns a short message rather than failing opaquely.

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?

The description is front-loaded with the core purpose, then moves efficiently through use cases, region semantics, alternatives, and output/error behavior. There is minor repetition of the region list, but it supports the guidance rather than bloating the text.

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 two-parameter read-only tool with full schema coverage and an output schema, the description supplies everything an agent needs: purpose, valid regions, defaults, output format, alternatives, and error behavior. No important invocation context 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 already 100%, so the baseline is 3. The description adds meaning by explaining the distinction between equity-market regions and asset-class regions and by warning that other country codes are not accepted, which clarifies how the enum should be interpreted in practice.

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 uses a specific verb-and-resource framing: it reports whether a market is open or closed for a region, along with session timing and an index summary. It explicitly contrasts market-wide scope against per-stock and sector tools, making it easy to distinguish from siblings such as get_stock_quote and get_sector_overview.

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 names concrete use cases ("is the US market open", market hours, quick index overview) and explicitly redirects individual-price and sector requests to the appropriate sibling tools. The boundary between this tool and alternatives is clear.

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