list_futures

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

Annotations only cover readOnlyHint/openWorldHint, but the description adds critical operational context: ~530 contracts, 700 KB (BASE) to 3.5 MB (ALL) of JSON, exceeding model context, with the realistic outcome that a client saves to file or refuses the result. This is exactly the behavioral disclosure annotations cannot provide.

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?

Front-loaded with purpose and sizing caveat, then alternatives, then args. The size figures (700 KB / 3.5 MB) are precise and decision-relevant rather than padding, and no sentence is redundant.

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 no output schema, the description adequately characterizes the return (all fields of ~530 contracts, payload size). Combined with the size warning and alternatives, an agent has what it needs, though it could note pagination/streaming absence explicitly.

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 0%, so the description must carry the load, and it partly does by glossing the enum values: BASE = 'tradeable' versus ALL. It doesn't explain the tradeable/non-tradeable distinction beyond one word, but the added meaning over the raw enum is genuine.

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?

States a specific verb and resource ('full reference list of futures contracts: every field of every contract') and explicitly scopes it as a bulk dump. It names the siblings it is not (find_instrument, get_future_by), so an agent can distinguish it from the other list_*/get_*_by tools without opening any 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?

Explicitly states when NOT to use it ('a dump for scripts, not something to read') and names two concrete alternatives with the exact selector argument (find_instrument with instrument_kind="futures", get_future_by for one). Both the routing condition and destination are given.

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