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

Annotations already declare readOnlyHint=false and idempotentHint=false, so the side-effectful nature is known. The description adds context beyond annotations: requires an API key, `value` is in minor currency units, defaults, and that the returned deal enters the pipeline at the first stage. It does not contradict any annotation and provides valuable operational detail.

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?

The description is divided into three focused paragraphs: purpose, usage guidance, and key implementation semantics. Every sentence adds value—no filler. It is front-loaded with the verb+resource statement, making it easy for an agent to quickly grasp the tool's core function.

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 create operation with 8 parameters but no output schema, the description covers essential behavioral nuances: duplicate-avoidance strategy, currency unit scale, default currency, pipeline entry, and return value. It gives enough context to use the tool safely and effectively, complementing the schema descriptions. No major gaps remain.

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 the baseline is 3. The description highlights the `value` unit convention (minor currency units) and the meaning of `leadEmail` as the key, but this information is already present in the schema (e.g., 'Deal value in minor currency units', 'Lead's email address'). The description adds minimal semantic value beyond the schema, so 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?

The description clearly states the tool's function: 'Open a new deal against a lead's email address.' It specifies the resource (deal) and the key parameter (leadEmail). It also differentiates from sibling `update_deal` by explicitly telling the agent to use `update_deal` for modifying existing deals.

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?

It explicitly states when to use: 'Use it when a conversation turns into a real opportunity worth tracking.' It provides a critical caution: 'it does not check for an existing one on the same email, so list_deals first if you might be duplicating.' It also names the alternative: 'To change a deal that exists, use update_deal.' This fully satisfies the when/when-not/alternatives criteria.

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