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

Goes beyond the annotations: it discloses the login requirement, that the operation is idempotent and returns success without error when nothing was followed, and a privacy trait (the counterparty can never see that you followed or unfollowed). These are substantive behavioral facts not present in the structured fields.

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?

Bracketed sections (login, when-to-use, chain, pitfalls) front-load the most decision-relevant facts and every line earns its place. No redundant restatement.

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 single-parameter mutation with no output schema, the description covers the auth gate, usage trigger, companion tool, idempotency, and visibility semantics, leaving nothing an agent needs to call it correctly.

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?

Only one parameter (productId) with 100% schema description coverage, so the schema already carries the meaning. The description adds no additional syntax, format, or sourcing guidance for productId, making this baseline-level.

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 names the specific verb and resource (取关产品 / 'this tool unfollows'), and the name/title make the action unambiguous against siblings like follow_product and unfollow_creator. It leans on the combination chain rather than a standalone 'what it does' sentence, so it's clear but not maximally explicit.

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 states when to use it (user says 'don't need to keep this') and pairs it with a concrete workflow: get_my_card to see current follows, then this tool to unfollow. The alternative/context is spelled out rather than implied.

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