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

The description reveals the key behavioral side effect: once set, every payment by the agent is automatically checked against the policy via policy.check. It also lists the rules applied. However, it does not mention whether the policy is immediately effective, if it can be updated, or any prerequisites (e.g., the agent must exist). Annotations already indicate it is not read-only, consistent with the write operation.

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 three sentences, each adding value: states purpose, lists rules, links to policy.check. It is front-loaded with the key action and perfectly efficient with no wasted words.

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 9 parameters (100% schema coverage), no output schema, and minimal annotations, the description is fairly complete. It explains the purpose and side effect. It could be more complete by clarifying the lifecycle (e.g., can policies be updated?) or that some parameters are optional, but the schema already handles that. The description suffices for a create 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%, so the baseline is 3. The description summarizes the rules (per-transaction ceiling, daily limit, etc.) roughly corresponding to parameters, but does not add new meaning beyond what the schema already provides. It offers a high-level overview but no extra 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 creates a spending policy for an AI agent, listing specific rules it sets (per-transaction ceiling, daily limit, etc.). It distinguishes from the sibling 'policy.check' by explaining that payments are checked against the policy automatically via that tool.

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 the tool is used to set up policies before payments, but it does not explicitly state when to use this tool versus alternatives like 'policy.delegate' or provide conditions for when not to use it. No exclusion guidance is given.

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