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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the bar is lower. The description adds genuinely useful behavior beyond them: partial-update semantics ('Only the fields you give are sent') and concrete mutation examples, so the agent knows unmentioned fields are preserved rather than cleared.

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 short sentences, front-loaded with the operation type and the partial-update rule, ending with the endpoint. Nothing is redundant and no sentence 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?

With annotations covering safety profile and a fully described 13-param schema, the description plus schema give an agent what it needs to invoke the tool. The main unaddressed point is what the call returns (no output schema) and any error behavior for an invalid deal id.

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 all 13 parameters including required deal_id, enums and ranges are documented structurally; baseline 3 applies. The description only gestures at current_state and deal_type_stage_id via examples and adds no format or constraint detail 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 ('change fields of a deal') and gives concrete examples of the most common writes (stage move, won/lost state). It is clearly an update tool, distinguishable from create_deal and get_deal, though it never explicitly names those siblings as contrasts.

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 implied by the WRITE prefix and the PUT /deals/{id} endpoint, and 'Only the fields you give are sent' tells the agent this is a partial update rather than a replace. There is no explicit when-to-use/when-not guidance or routing to alternatives such as create_deal or list_deal_types for discovering stage ids.

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