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

Annotations already declare non-read-only, destructive, and idempotent behavior, so the baseline is low. The description meaningfully adds that this is a merchant-side action gated behind Builder tier or higher, which is real prerequisite information not encoded in annotations. It does not explain side effects of rejection (e.g. whether existing links/partnership data are removed), which would matter for a destructiveHint tool.

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 short sentences, front-loaded with the action, then the value mapping, then the prerequisite. No filler or redundancy.

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 three-parameter, annotation-covered mutation with no output schema, the description covers purpose, decision semantics, and the tier prerequisite. The remaining gap is outcome transparency: it does not say what a rejection does to existing partnership state or what the caller gets back, which is notable given destructiveHint=true.

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% and the status enum is documented inline, so the schema already carries essentially all parameter meaning. The description restates the status mapping but adds nothing about the program_id versus partnership_id distinction or where those IDs come from. Baseline 3 applies.

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 (approve or reject) applied to a specific resource (a partner who applied to an affiliate program), and immediately disambiguates it from program-level siblings like update_affiliate_program or list_affiliate_partners. An agent can tell what this does without opening the schema.

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?

Gives clear when-to-use context (merchant reviewing a partner application) and maps each enum value to a real-world decision (approve vs decline). It also states a prerequisite (Builder tier or higher). It does not name an alternative tool or say when not to use this, which keeps it just short of a 5.

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