market_hours

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

With no annotations, the description carries the burden of behavioral disclosure. It adds the key detail that the tool returns null when the API has no hours, which is useful. However, it does not explain what 'status' entails, potential error conditions, or any other behavioral traits beyond the null case.

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 a single, compact sentence that conveys the core purpose and a critical edge case. It is appropriately sized, with no redundant words or padding.

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?

The tool is simple with one parameter and an output schema, so the description need not detail return values. However, it lacks usage context, such as which instruments are supported or how it differs from the similar 'market_hours_for_order_book' tool. The null mention adds edge-case context, but overall completeness is moderate.

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 input schema has only one parameter with no description (0% coverage). The description mentions 'an instrument' but does not explicitly elaborate on the instrument_id parameter's meaning or expected format, leaving the agent with minimal semantic guidance beyond the parameter's title.

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 clearly states the tool provides trading sessions and status for an instrument, which is a specific resource. However, it lacks a strong verb like 'get' or 'retrieve', and doesn't explicitly differentiate from the sibling tool 'market_hours_for_order_book', though 'for an instrument' implies general use.

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?

No guidance is provided about when to use this tool versus alternatives. It does not mention the existence of 'market_hours_for_order_book' or any other selection criteria, leaving the agent to infer usage context.

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