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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces this with "sending nothing" while adding genuinely new behavior: the preview_id is valid only 30 seconds, which explains the non-idempotent, ephemeral nature of the call. It does not detail what happens on a failed check or what the caller must do if the preview expires, so it stops short of a 5.

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 the purpose and the safety qualifier, then usage, then the parameter recipe, then the return and next step — a sensible order with no filler sentences. The telegraphic fragment style in the entry-styles clause ("market, nothing; limit, ...") is dense but slightly cryptic on first read.

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 16-parameter order-preview tool with an output schema, the description covers the essential pieces: validation scope, required inputs per entry style, the ephemeral preview_id, and the handoff to execute_previewed_order. Remaining gaps (what a failing check returns, how to refresh an expired preview) are modest given the output schema exists.

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 94%, so per-parameter meaning is largely already documented. The description's real contribution is cross-parameter combination rules by entry style (market needs nothing; limit needs order_type "limit" plus price; a waiting entry uses trigger_price; a ladder uses order_type "limit" plus ladder_prices), which the schema states only partially and scattered per property. This is above a pure baseline but not exhaustive across all 16 parameters.

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 ("Check a perpetual futures order and its stop-loss against the permissions, limits and price band") plus the crucial scope qualifier "sending nothing". This clearly separates it from execute_previewed_order and from close_position without needing the 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?

Gives an explicit when-to-use rule ("Use before every new position"), an explicit when-not with a named alternative ("Not for closing (use close_position)"), and the required follow-up call ("Next: execute_previewed_order(preview_id)"). The workflow position of the tool is fully determined.

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