Brex MCP Server

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

With no annotations provided, the description carries the full burden and does well by disclosing key behavioral traits: it's a write operation (explicitly noted), returns upload URL and matching details, and has a 30-minute expiration for matching. However, it lacks details on authentication needs, rate limits, or error conditions.

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 efficiently structured in three sentences: first states the core function, second specifies the return values and expiration, third clarifies the operation type. Each sentence adds critical information with zero waste, making it front-loaded and appropriately sized.

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 no annotations and no output schema, the description compensates well by explaining the write nature, return values, and expiration. It covers the essential context for a mutation tool, though it could improve by detailing output structure or error handling more 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 100%, so the schema already documents all three parameters thoroughly. The description adds no additional parameter semantics beyond what's in the schema, maintaining the baseline score of 3 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 specific action ('Create a pre-signed S3 URL for uploading a receipt') and the outcome ('that will be automatically matched with existing expenses'), distinguishing it from sibling tools like 'upload_receipt' which lacks the matching aspect. It precisely defines the verb+resource combination with a distinct purpose.

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 implies usage for receipt uploads with matching, but provides no explicit guidance on when to use this tool versus alternatives like 'upload_receipt' (which lacks matching) or other expense-related tools. It mentions the 30-minute expiration as a constraint, but doesn't specify prerequisites or exclusions.

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