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 authentication requirements, which is useful, but lacks details on rate limits, error conditions, response format, or whether this is a read-only operation (implied by 'Get' but not explicit). For a tool with no annotations, this leaves significant gaps in understanding its behavior.

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 a single, efficient sentence that front-loads the purpose and includes essential context (authentication). There is no wasted verbiage or redundancy, making it highly concise and well-structured.

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 tool's complexity (single parameter, no output schema, no annotations), the description is minimally adequate. It covers the purpose and authentication but lacks details on return values, error handling, or behavioral traits. Without annotations or output schema, more context would improve completeness for a financial tool.

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 100%, with the parameter 'subaccount_id' fully documented in the schema. The description adds no additional parameter semantics beyond what the schema provides, such as examples or constraints. Baseline score of 3 is appropriate as the schema handles the heavy lifting.

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 verb ('Get') and resource ('detailed margin information for a subaccount'), specifying the types of margin data retrieved (maintenance margin, initial margin, margin ratio). It distinguishes this from siblings like get_account or get_balance by focusing on margin-specific metrics, though it doesn't explicitly contrast with all siblings.

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 includes 'Requires authentication,' which is a basic prerequisite but not a usage guideline. It provides no guidance on when to use this tool versus alternatives like get_account (which might include margin data) or margin_watch (which might monitor margin changes), nor does it specify any exclusions or contexts for use.

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