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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so safety is covered. The description adds real value beyond that: it discloses the enumerated return fields (IDs, slugs, line metadata, units, release hash, attribution) and warns the result set is intentionally small. It does not mention auth or rate-limit behavior.

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?

Three sentences, front-loaded with purpose before scope caveat and use cases; the enumerated return-field list is dense but earns its place given no output schema exists. Minor verbosity in the field list, but 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?

With no output schema, the description carries the return-value burden and does so by enumerating the fields returned. Combined with scope bounds and use cases, an agent has nearly everything needed; only pagination mechanics (deferred to schema) are left implicit.

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%, so the schema already documents all five parameters including the two enums and their bounds. The description adds no param-level syntax or format detail, so the baseline 3 applies.

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 (List and search) plus resource (aggregate U.S. balance-sheet and debt series in the Fed Z.1 snapshot), and explicitly bounds scope with 'deliberately small catalog' and 'This is not the full Z.1 universe', which distinguishes it from fed_z1_series and fed_z1_snapshot without opening their schemas.

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?

Gives concrete trigger examples ('what household balance-sheet measures are available?', 'find the mortgage debt series') and a routing rule ('resolve a series before another Z.1 call'). It stops short of naming the sibling Z.1 tools to use instead, so the guidance is clear but not exhaustive.

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