Derive MCP

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions 'Requires authentication', which is a useful behavioral trait, but lacks other critical details such as whether this is a read-only operation, potential rate limits, error handling, or the format of returned data. For a tool with no annotations, this leaves significant gaps in understanding its behavior and constraints.

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 concise and front-loaded, consisting of two sentences that efficiently convey the tool's purpose and a key requirement. There is no wasted text, and it directly addresses what the tool does and a necessary condition ('Requires authentication'), making it appropriately sized for its content.

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?

Given the complexity of retrieving financial positions with no annotations and no output schema, the description is incomplete. It mentions authentication but omits other behavioral aspects like safety (read-only vs. destructive), response format, or error cases. For a tool that handles sensitive financial data, this lack of context makes it insufficient for an agent to fully understand how to use it effectively.

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 100% description coverage, providing clear documentation for all parameters (subaccount_id, currency, instrument_type). The description does not add any additional meaning beyond what the schema already states, such as explaining parameter interactions or default behaviors. With high schema coverage, the baseline score of 3 is appropriate, as the description relies on the schema for parameter details.

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's purpose: 'Get all open positions for a subaccount' with specific details like 'unrealized PnL, mark price, leverage, and liquidation price'. It uses a specific verb ('Get') and resource ('open positions'), but does not explicitly differentiate from sibling tools like 'get_account' or 'get_balance', which might also retrieve financial data. This makes it clear but not fully sibling-distinctive.

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 minimal usage guidance: it mentions 'Requires authentication', which is a prerequisite, but offers no explicit advice on when to use this tool versus alternatives. For example, it does not compare to 'get_account' for general account info or 'get_balance' for specific balances, leaving the agent to infer usage from context without clear exclusions or alternatives.

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