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

Annotations only declare the safety profile (write, non-readonly, destructive, not idempotent); the description adds real behavior beyond that, notably that external_id makes retries collapse to a single count and that the first result comes back with 200. It does not explain what happens when click_id is unknown or invalid, and the destructiveHint=true flag is never contextualized, but the added dedupe semantics are genuinely valuable.

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 with zero filler, front-loading what the tool does before the parameter hints. Each clause (tk mapping, cents unit, dedupe guard) carries information the agent needs at call time.

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 required parameter, full schema coverage, and no output schema to explain, the description covers the action, the key inputs, and the retry-safety rule. Remaining gaps (error behavior on an unknown click_id) are minor for a simple event-reporting write.

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 every parameter is already documented in the schema, including the tk mapping, the cents unit, and the dedupe behavior of external_id. The description largely restates those definitions rather than adding new meaning (e.g., whether name has a default, or how value_cents is aggregated). Baseline 3 is appropriate.

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?

A specific verb ('Report a sale or sign-up') plus a precisely scoped resource ('from someone who came through a tracked link') tells the agent exactly what gets created. It is clear, but it never distinguishes itself from the sibling 'track_event' or references 'list_conversions', so the agent must infer which write path to use.

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?

The opening sentence implies the triggering condition (a sale or sign-up attributed to a tracked link), which is useful context. However, there are no explicit when-not conditions, no prerequisites (e.g., the click must already exist via create_link), and no named alternative such as track_event or list_conversions.

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