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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds a genuinely non-structured behavioral fact — 'Draws no credit' — telling the agent this enumeration is free against any quota, which is exactly the kind of context annotations cannot express.

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?

Two compact sentences with the resource identity front-loaded and the downstream-use note second. The filler 'and so on' slightly dilutes the otherwise tight phrasing but does not harm selection.

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 parameterless, read-only catalog lookup with full annotation coverage, an agent has enough to select and invoke it: what it returns, why it matters (slugs), and that it costs nothing. No output schema exists, but the description states the key returned field, so nothing critical 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?

Zero parameters, so there is nothing for the description to disambiguate; baseline for a parameterless tool applies. The only semantic content needed is what the call returns (slugs), which the description does supply.

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 the exact resource (every US economic series Helious tracks), illustrates it with concrete examples (CPI, payrolls, GDP), and states the payload value (each series' slug). It implicitly contrasts with get_series, the per-series fetch tool, though it never uses an explicit verb like 'list' — the enumeration intent is inferred from 'Every ... series ... with its slug.'

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?

'with its slug for get_series' establishes the intended two-step workflow: discover a slug here, then call get_series. It gives clear positive context but no explicit exclusions or when-not-to-use guidance (e.g., call get_series directly if you already know the slug).

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