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

The readOnlyHint annotation already establishes this is a safe read. The description adds real behavioral context beyond the annotation: counts are computed live (not cached) and licenses are included in the output. It does not mention pagination, result size, or ordering, which is a minor gap for a list endpoint.

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?

A single front-loaded sentence that lists the resource, the payload contents, the freshness characteristic, and the cost in one pass. No 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 zero-required-param list tool with no output schema and safety covered by annotations, the description tells the agent what it will receive (sources with licenses and live counts). Only the return shape and volume details are absent, which is acceptable at this complexity.

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% and the single 'contains' parameter is documented in the schema with a case-insensitive substring example. The description adds nothing about the filter, so the 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?

States a specific verb and resource ('List the Econ Data Library's sources') and enriches it with the content of each entry (licenses, live counts) plus the kinds of sources covered. It doesn't explicitly differentiate from siblings like search_econ_series, but no sibling overlaps this resource, so the risk of confusion is low.

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?

'Free' hints at when this is preferable to paid alternatives, and the resource-orientation implies using it to survey available sources before drilling into series. There is no explicit when-to-use statement, no prerequisites, and no named alternative.

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