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

The description reveals critical behavior beyond the annotations: credentials are saved regardless of whether the connection test succeeds, and the operation is subject to plan limits. This materially changes how an agent should invoke the tool, so the disclosure is valuable.

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, each earning its place: the purpose, the critical testing caveat, and the plan-limit constraint. No filler or redundancy.

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-style tool with a nested config object and no output schema, the description covers the essential operational context: test first, settings persist even on failure, and plan limits apply. The schema handles parameter details, so nothing critical is missing.

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 input schema already documents name, type, and config. The description adds no parameter-specific semantics beyond the high-level mention of databases and spreadsheets, which is consistent with the baseline for full schema coverage.

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 states a specific action and resource: connect a new database or spreadsheet to your workspace. This clearly distinguishes it from sibling tools like get_data_source, update_data_source, and delete_data_source by signaling that it creates a new connection.

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 names the alternative test_data_source_connection and instructs the agent to use it first, warning that add_data_source saves settings even if they don't work. It also notes the plan data source limit, giving a clear condition on when adding may fail.

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