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

Annotations give destructiveHint=true, but the description goes well beyond that by naming the exact consequence: the old token stops tracking immediately and already-shared links break. It also discloses the rewardful API route (PUT /v1/affiliate_links/:id), which aids error diagnosis. This is real behavioral context the structured fields do not carry.

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 purpose and then the destructive warning at the point of highest salience, followed by the remedy and the underlying endpoint. Zero filler.

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 two-param mutation with annotations covering the safety profile and no output schema, everything an agent needs is present: what changes, the destructive side effect, the safer alternative, and the API path. Nothing material is missing.

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 both parameters (link_id UUID, token pattern) are already documented in the schema. The description adds no parameter-level detail or format hints beyond it, which is the baseline when the schema does the heavy lifting.

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 ('Change the token of an existing affiliate link') and distinguishes itself from the create sibling, which the agent would otherwise confuse it with. The agent can select this over rewardful_create_affiliate_link without opening either 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?

Explicitly names the alternative ('Prefer rewardful_create_affiliate_link to add a second token') along with the condition that selects it, plus a warning about when this tool is the wrong choice. The when-not guidance is unusually concrete.

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