Update a product input

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

Annotations already indicate readOnlyHint=false and destructiveHint=false, so mutation is expected. The description adds value by explaining sparse-update semantics, the behavior when update_mask is omitted (all populated fields applied), the return of the updated ProductInput, and the async refresh after minutes. This goes beyond the structured annotations, though it does not elaborate on failure modes or idempotency, which the annotations already flag.

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 dense sentences. The first sentence fronts the purpose and benefit. The second covers essential parameter semantics. The third states the return value, async behavior, and alternative tool. No filler, every sentence earns its place.

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?

The tool is moderately complex with 7 parameters and nested objects, and there is no output schema, so the description must cover return values. It does: 'Returns the updated ProductInput' and explains the async processing. It also mentions the data_source prerequisite and the insert alternative. It does not describe error handling or exhaustive edge cases, but for the complexity level it is sufficiently complete.

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 adds meaning by explaining data_source as 'the source holding the input' and update_mask as 'a comma-separated list of attribute paths' with the omission behavior. This enriches the schema definitions significantly, especially for the two most context-dependent parameters.

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 uses a specific verb+resource: 'Sparse-updates an existing product input' and immediately clarifies it's the 'cheap way' to change price/availability without re-sending the whole product. It clearly distinguishes from insert_product_input for create/replace, and from delete_product_input by context. This is a model of purpose clarity.

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?

Explicitly states when to use this tool: to change price or availability without re-sending the whole product. It names the alternative: 'To create a product or replace it wholesale use insert_product_input.' Also specifies a prerequisite: data_source must be the source holding the input. This is explicit use-vs-alternative guidance.

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