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

Annotations declare readOnlyHint=false and openWorldHint=true, implying a side-effecting, external-facing call (likely a checkout/session URL), but the description never explains what the returned link is, whether anything is created, or any auth/limits. It adds routing context but no behavioral disclosure beyond the annotations.

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 sentences, purpose front-loaded, the long trigger list is justified because it is the routing logic, and the parameter instruction is placed last where it is needed.

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 one optional param, 100% schema coverage and no output schema, the definition is nearly complete; the only gap is that the return value ('a link') is only implied rather than described in any detail.

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 100% with an enum, setting the baseline at 3, but the description goes further by mapping user intent to value: 'year when the user asks for the annual, yearly, or discounted plan; otherwise leave it monthly.' That is genuine semantic value beyond 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: 'Give the signed-in user a link to upgrade to Klyf Pro.' No sibling occupies this space (all siblings are analytics/content/reply tools), so the agent can identify it instantly.

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 enumerates the trigger utterances (upgrade, subscribe, go Pro, pay, unlock, remove limits, ask about auto-reply) and even routes the interval choice by user phrasing. This is textbook when-to-use guidance.

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