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

No annotations are provided, so the description carries the full burden. It discloses key behavior: buyer role, monthly limit enforcement by buy, and that null removes the limit. It omits auth/permission details and effects on already-pending purchases.

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?

One compact sentence with front-loaded buyer role and semicolon-separated behavior. Every clause adds value without repetition.

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 simple two-parameter mutation tool with no annotations or output schema, it covers purpose and null behavior, but leaves currency selection/default and numeric units unclear, so an agent may need external assumptions.

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 coverage is 0%, so the description must compensate. It explains null semantics for monthly_budget_minor and implies monthly cadence, but never mentions the currency parameter or units, leaving one of two parameters undocumented.

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 and resource ('set a monthly spending limit'), scopes it to Buyer, and explains its interaction with the buy sibling ('buy refuses anything above what is left'). An agent can distinguish this from buy and understand its intended effect.

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?

Clear context: buyer uses this to cap spend, and null removes the cap. It implies when to set or remove the limit, but does not explicitly state prerequisites or alternatives beyond the buy interaction.

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