Historical OHLC bars

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

The description adds significant behavioral context beyond the annotations: it notes volume is only available where applicable, FX returns bid/ask OHLC, the max bars per call (1200), and how to page further back. These details are not in the annotations and are crucial for correct invocation and interpretation.

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, using only two sentences. It front-loads the core purpose, then efficiently lists horizon values and paging behavior, with no wasted words or redundant information.

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 description covers the main return content (OHLC, volume, FX specifics), the bar-size enumeration, and paging mechanics, which are sufficient for a read-only tool. It does not explicitly describe the exact response structure (e.g., array of bar objects), but that is reasonably implied and not critical given the lack of an output schema.

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 description provides essential meaning for the horizon parameter, which is completely undocumented in the schema, by listing all valid minute values and their daily/weekly/monthly equivalents. It also clarifies paging behavior with time and mode, adding value beyond the schema's brief descriptions.

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 identifies the tool as returning historical price bars (OHLC, volume) and explains the horizon meanings, which is specific and unambiguous. However, it does not explicitly distinguish this tool from sibling get_instrument_price, though the title 'Historical OHLC bars' and the focus on historical data imply the difference.

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 provides usage guidance for paging (pass time + mode) and explains horizon values, but it does not mention when to use this tool vs alternatives like get_instrument_price. There is no explicit 'use this for historical data, use that for current price' guidance, leaving the agent to infer the distinction from context.

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