Create an API data source

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

Although annotations indicate the tool is not read-only (readOnlyHint=false) and not destructive, the description adds important behavioral constraints such as conditional parameter requirements ('content_language and feed_label must be both set or both omitted') and the return value (DataSource with dataSourceId). This goes beyond what annotations alone convey, though it does not disclose error conditions or idempotency details.

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 four sentences long and dense with necessary information, front-loading the core purpose. Each sentence serves a purpose, from usage context to conditional rules. It is longer than minimal examples, but the complexity of the tool (7 parameters, conditional logic) justifies the length.

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 description captures the tool's essential context: what it creates, why it's needed, key parameter constraints, and the return value. It does not explain behavior on invalid input or specific account defaults, but those are covered in the schema. Given the lack of an output schema, the description does enough to guide correct invocation.

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?

The input schema already provides 100% coverage with descriptions for all parameters. The description rephrases and summarizes some parameter relationships (e.g., 'countries applies to primary sources only') but does not introduce substantial new meaning beyond the schema. It provides a useful high-level recap but remains at the baseline for schema-heavy tools.

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 action: 'Creates an API (generic) data source' and explains its role as the target needed by other tools (insert_product_input, update_product_input, insert_promotion). It distinguishes itself from sibling tools like list_data_sources and get_data_source by focusing on creation.

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?

The description explicitly provides when-not guidance: 'Only API sources can be created through the API (file, UI and autofeed sources are set up in Merchant Center)' and indicates when to use it as a prerequisite for other data input tools. This effectively steers the agent away from inappropriate uses.

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