get_market

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds valuable behavioral context: the 'status' field is null for non-US keys due to an upstream limitation, not an error. This prevents an agent from misinterpreting null results as failures. It also clarifies that the index summary works for all keys, which is useful behavioral information beyond the annotations.

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 compact and front-loaded: the first sentence states the core purpose, the second gives example questions and the key-vs-ticker distinction, and the third covers the US-only status limitation. Every sentence earns its place, and there is no redundant filler.

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 single-parameter, read-only tool with a rich schema and an output schema, the description is complete. It covers what the tool does, how to use it, the key limitation (US-only status), and what to expect for other keys. An agent has everything needed to invoke it correctly without further investigation.

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%, so the schema already documents the 'key' parameter thoroughly, including the allowed values and the US-only status behavior. The description reinforces this by giving examples ('US', 'EUROPE') and restating the key distinction (market key vs ticker). This adds a small amount of clarity beyond the schema, but the schema does most of the work, so a 4 is appropriate rather than a 5.

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 verb ('Get'), a clear resource ('trading status and headline index summary for a market'), and explicitly distinguishes itself from ticker-based tools by saying it takes a market key, not a ticker symbol. It also names the sibling 'get_quotes' implicitly by contrast, making it easy for an agent to select this tool for market-level status rather than individual securities.

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 says when to use this tool: to answer whether a market is open, when it opens/closes next, and how major indices are doing. It also gives an exclusion: it is not for ticker symbols, and it notes that 'status' is only available for 'US'. This is clear guidance that prevents misuse.

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