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. It effectively discloses key behavioral traits: it's a read operation ('List'), supports filtering and pagination, and describes the return format ('detailed limit configurations including base limits, buffer percentages, and merchant category controls'). However, it doesn't mention rate limits, authentication requirements, 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 two sentences: the first states the core purpose and key features, the second describes the return format. Every sentence adds value with zero wasted words, and the most important information is front-loaded.

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 read operation with no annotations and no output schema, the description provides good coverage of purpose, behavior, and return format. It adequately compensates for the lack of structured output schema by describing what's returned. However, it could be more complete by mentioning authentication requirements or error handling.

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 fully documents all 5 parameters. The description adds minimal value beyond the schema by mentioning filtering by member user and pagination support, but doesn't provide additional semantic context about parameter usage or interactions. The baseline of 3 is appropriate when the schema does 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 ('List') and resource ('spend limit policies') with specific details about what's included ('authorization settings and spending controls'). It distinguishes from sibling tools like 'get_spend_limit' (singular) by indicating it returns multiple policies with filtering capabilities.

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 through mentioning filtering capabilities ('Supports filtering by member user and pagination'), but doesn't explicitly state when to use this tool versus alternatives like 'get_spend_limit' (singular) or other budget-related tools. No specific exclusions or prerequisites are mentioned.

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