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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds value beyond that by disclosing the underlying endpoint (GET /datasource), the fact that rows are suppressed unless return_rows is true, and the pagination contract - behavior an agent cannot infer from the annotations.

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 compact clauses: what is returned, the row-returning condition with paging, then the endpoint. The return payload is front-loaded and no sentence is padding.

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?

No output schema exists, so the description carries the burden of describing the response, and it does (headers, TotalRows, row page, page_no continuation). It stops short of noting that no parameters are required - i.e. that at least one of id/external_id must be supplied - which is the one thing an agent could still get wrong.

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?

With 100% schema description coverage, the schema already documents id, external_id, page_no, page_size and return_rows, so the baseline is 3. The description usefully frames id vs external_id as an either/or and restates the return_rows sentinel, but adds no formats, bounds or defaults beyond what the schema already carries.

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 ('One data source by id (GUID) or external id') plus exactly what comes back (column headers, TotalRows, optional row page). The singular 'one data source' implicitly separates it from the sibling list_data_sources, so an agent can pick correctly without opening a schema.

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?

Gives operational guidance for the parameters ('Rows are only returned when return_rows is true; page through them with page_no'), which tells the agent how to page. It never says when to choose this over list_data_sources or search_entries, so the when-to-use layer is implied rather than stated.

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