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

readOnlyHint=true already establishes the safe-read profile, so the description only needs to add what annotations cannot. It notes the list is cursor-paginated and that records are "usually discount codes", but pagination is already covered by the cursor parameter description and there is no mention of auth scopes, rate limits, or ordering guarantees.

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?

Three tight sentences: what the resource is, the fields returned, the key usage pattern, pagination behavior, and the backing endpoint. Nothing is redundant and the most important content 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?

With no output schema, the description compensates by naming the returned fields, and it flags pagination for a 6-parameter list endpoint. Only a note on default ordering/date scoping (updated_at_min) would make it fully self-sufficient.

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 67%, so the schema handles most of the burden, but the description adds practical meaning to customer_id (answering "what codes does this customer have?") and frames fulfillment_status/usage_status alongside their observed values. limit, cursor, and updated_at_min are left entirely to the schema.

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 ("List rewards that have been issued to customers — usually discount codes") and even enumerates the returned fields (code, fulfillment_status, usage_status, used_at, expires_at). No sibling tool covers reward fulfillments, so there is no ambiguity to resolve.

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 concrete usage pattern: "Use customer_id to answer 'what codes does this customer have?'", which tells the agent when this tool is the right call. It stops short of stating when-not to use it or naming an alternative path, but the context is clear.

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