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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds that results include a deal description, races, and referral-linked URLs, which is genuinely useful given no output schema exists. It says nothing about behavior on an unknown slug, rate limits, or referral-code handling.

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 short sentences, front-loaded with what the tool returns followed by the usage condition. No padding or redundant phrasing; every clause carries information.

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 one-parameter read tool with full annotation coverage, the description supplies the key missing piece – roughly what comes back (details plus referral-coded links). Edge behavior such as a stale or unknown slug is not addressed, but that is a minor gap for this complexity level.

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% and the single slug parameter is documented in the schema as coming from the cp0x catalog with a 100-char max. The description only restates that the slug must be known, adding nothing beyond the schema, so the baseline 3 applies.

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 ("Get a cp0x deal") and even names the payload fields returned (description and races), which is more than a restatement of the title. It does not explicitly distinguish itself from the sibling list_deals, leaving that inference to the agent.

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?

"Use this when a deal slug is known and its full details are needed" gives a clear triggering condition and implicitly excludes discovery-only cases. No alternative (e.g. list_deals for finding slugs) is named and no when-not case is stated, so it stops short of a 5.

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