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

With only readOnlyHint=false available, the description carries real weight and delivers: it discloses that `contact` becomes visible to the counterparty after a deal closes, that the webhook fires on new bids or messages, that the URL must be https, and that an empty string cancels the webhook. That is meaningful behavioral context beyond the single annotation. It does not state permissions or whether unspecified fields are left untouched.

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?

A single dense sentence with no filler; the most decision-relevant content (what the counterparty sees) comes first and the cancellation rule is appended. It is slightly overloaded — splitting the contact and webhook clauses would improve scannability — but nothing is wasted.

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 mutation tool with no output schema and minimal annotations, the description covers the two writable fields well but leaves open whether this creates the account on first call (the title 設定帳號 suggests setup, the name suggests update) and whether omitting a field leaves it unchanged or clears it. Those gaps matter for calling it correctly on a partial update.

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 only 33% (only `api_key` is documented), so the description must compensate, and it does for both remaining parameters: it explains the semantic role of `contact` (counterparty-visible after deal) and the format/cancellation semantics of `webhook_url` (https required, empty string disables). `api_key`'s fallback role is covered by the schema itself, so nothing critical is left unexplained.

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 a concrete verb (設定) and enumerates the exact account fields being configured: the contact info shown to counterparties after a deal, and the notification webhook. This is clearly distinguishable from siblings like update_listing or deal_action, which operate on listings and deals. It is not quite a 5 because the description frames it as two field settings without stating the overall scope of the account object being modified.

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?

Usage is only implied: an agent can infer you call this to configure your contact method or notification webhook. There is no explicit 'use this when...', no prerequisites (e.g., must have an account/deal flow set up), and no named alternative among the 17 siblings. The `webhook_url` empty-string convention is the closest thing to a conditional, but it is a parameter rule, not usage guidance.

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