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

Annotations already mark it read-only, and the description goes beyond that by revealing the response's conceptual structure (data views, advanced settings, catalogs) and the non-obvious semantics of flags like single, requires_metric, deprecated, and custom, as well as the data-view scoping rule. No side effects are implied.

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 front-loaded with a clear verb and resource, and every clause carries substantive information; no filler. It is long, but the density is justified by the conceptual complexity of the returned metadata.

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 read-only, two-parameter tool with a full output schema, the description covers the key concepts an agent needs before calling it and explicitly ties it to the widget-building workflow. Nothing important appears 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 coverage is 100% and both parameters already have descriptions. The tool description adds contextual meaning about data_view scoping and flags, but it does not significantly enrich the parameter descriptions themselves, so a baseline 3 is appropriate.

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 verb ('Describe') and resource ('datasource'), scoped to 'the way the report builder sees it', and enumerates the exact contents (data views, advanced settings, defaults, metric/dimension catalogs). It also distinguishes this from sibling listing tools by naming its downstream consumers, add_data_widget and update_data_widget.

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?

It explicitly says 'Use this before add_data_widget or update_data_widget', which gives a concrete trigger for choosing it. It does not explicitly say when not to use it or name alternatives like datasources or connected_datasources, so it stops short of full alternative routing.

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