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

No annotations are supplied, so the description carries the burden, and it does disclose meaningful behavior: entitlement-gated visibility when an API key is present, the fact that canonical variable names originate here, and the list-vs-detail mode switch. It stops short of describing pagination, response size, or rate limits, but the presence of an output schema covers the return-shape gap.

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?

Front-loaded with the purpose and the ordering rule before the Args block, and every sentence adds information. Slightly long for a two-parameter tool, but the extra lines on canonical names and entitlement gating are load-bearing rather than filler.

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 listing tool with an output schema already defining the return shape, the description covers everything needed to invoke correctly: the ordering constraint relative to get_data, entitlement behavior, and both parameter modes. Nothing an agent must know before calling 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 0%, so the description must compensate, and it does: source_id is explained in both modes ('omit to list every visible source', 'give one e.g. "gadr"') along with what detail is returned (canonical variable names, units, row limits, filterable columns). output_format is given defaults and relative sizing ('csv', compact, default) beyond the raw enum values.

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 ('List the AQUAVIEW data sources') plus the dual mode (list vs. describe one in detail). It also implicitly separates itself from get_data and search_datasets by scoping to 'sources you can pull actual rows from' and positioning itself as the source of canonical variable names.

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?

Explicit sequencing rule: 'Call this BEFORE get_data on a source you have not used,' which names the alternative tool and the exact condition that selects this one. It further justifies the call by noting variable names are canonical and cannot be guessed, so the agent knows why the prerequisite exists.

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