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

Annotations already establish read-only, idempotent, closed-world, non-destructive behavior, so the safety burden is covered. The description adds real value beyond that: it enumerates the status vocabulary (live, paused, hand entry, not collected), flags that agencies may be late with series, and warns that figures are exactly as published with period/retrieval-date/source. These are behavioral traits not encoded anywhere in 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?

One long run-on sentence plus several fragments that bundle data-usage policy, a coverage-format warning, a citation obligation, and a 'not investment advice' disclaimer into a tool definition. The field list is front-loaded, but the closing sentences about notices and advice do not help an agent decide to call the tool and dilute the actionable content.

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?

With no parameters and no output schema, the description carries the full burden of explaining the return shape, and it does list the field names plus the possible status values. It is still ambiguous about the structure of the response (flat list? nested per-agency series?) and about what 'any series the agency itself is late with' actually looks like in the payload.

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. The field enumeration in the description functions as informal output documentation rather than parameter guidance.

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 names a specific resource and enumerates the returned fields (name, homepage, terms URL, required notice, status), so an agent can tell this is the agency/provenance catalog rather than a data-fetching tool. However the verb is only implied ('Every source agency:') and no sibling (latest, search_series, series_history) is named for contrast, so differentiation is inferred rather than stated.

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?

Usage guidance is present but oriented toward consuming the data ('read the coverage line', 'Repeat each figure's notice when you use it') rather than toward tool selection. There is no explicit statement of when to call list_sources versus the sibling series tools, and no exclusions, so the agent must infer that this is the provenance/terms lookup.

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