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

Annotations already declare readOnly=false, idempotent=false, destructive=false and openWorld=true, so the safety profile is largely covered. The description adds the ordering constraint (set before approval) and the optional nature of payees, but says nothing about overwrite semantics for an existing policy, auth requirements for api_key, or currency handling — notable gaps for a non-idempotent write.

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?

Two tight sentences with the core action front-loaded and the prerequisite placed last as a constraint. No filler, though the opening could have named the tool's read mode implied by its title.

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 6-parameter, non-idempotent write with no output schema and only 33% schema coverage, the description leaves real gaps: it never explains the 'read' behavior its own title advertises, nor the agent/api_key/currency parameters, nor what the response looks like.

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 only 33%, and the description compensates partially by glossing per_tx ('most it may pay in one go'), daily ('per day') and payees ('allow-list of payees'). It leaves api_key, agent and currency unexplained, and does not resolve the tension between the schema's 'in pounds' wording and the presence of a currency parameter.

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 the spending limits for an AI agent') and enumerates the dimensions it configures (per-payment, per-day, optional payee allow-list). It is clear enough to distinguish a policy-setting tool from siblings like sebbi_spend_request or sebbi_spend_verify, though it never names them.

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?

Provides a genuine lifecycle prerequisite ('Must be set before the agent can be approved to spend'), which tells the agent when this must happen. However it gives no exclusions and does not contrast with the spend_request/spend_verify siblings that operate on an already-configured policy, so the routing is only implied.

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