List open positions

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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), but the description adds substantive operational context the annotations cannot convey: the required `portfolio:read` scope and the concrete 60 req/min rate limit shared across the `venue-private` group, including that these calls also consume the venue's own allowance. It is slightly thin on what a position record contains, which is the only reason this is not 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-loads the resource being listed in the first sentence, then layers auth and rate-limit context as separate ideas. The rate-limit paragraph is a long compound sentence, but each clause (shared allowance, avoid polling, prefer venue filter, use the stream) carries distinct guidance.

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?

Covers authorization, rate limits, and polling strategy for a zero-parameter read tool, and the safety profile is already declared in annotations. With no output schema, it stops short of indicating the return shape (e.g. instrument, size, entry price), which would help an agent consume the result.

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 tool takes no parameters (0 params), so the baseline expectation is 4. The description adds nothing parameter-related, but there is nothing to describe.

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+resource ('Open derivative positions') and scopes it ('across the account'), which cleanly separates it from list_balances and list_open_orders. The line 'Name a venue when you only need one' implicitly routes to the venue-scoped sibling, sharpening the distinction further.

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 explicit when/when-not guidance: use a venue-specific call when only one venue is needed, and follow the order stream instead of polling this endpoint. It even names the alternative mechanism (fill reporting on the stream) rather than leaving the agent to infer it.

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