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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, openWorldHint, destructiveHint=false), so the bar is lower. The description adds no further behavioral context — no pagination behavior, default row behavior, rate limits, or what happens with invalid series IDs — but it doesn't contradict annotations either.

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 short sentences, front-loaded with the primary purpose and followed by the optional parameters. Efficient overall, though trailing 'etc.' and bare code abbreviations leave some ambiguity that a slightly more explicit phrasing would remove.

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 series-observation query with a fully documented schema and no output schema, the description gives enough to call the tool correctly (identifier required, optional time/transform/aggregation controls). Return-value format is not described, but that is a minor gap for a well-known time-series shape.

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%, so the schema fully documents all seven parameters (start/end, limit, units, frequency, aggregation_method, series_id). The description restates the units codes ('lin, chg, pch, log') and frequency codes ('m, q, a'), which the schema already provides in greater detail, adding no meaning beyond it.

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?

Specific verb ('Get') plus resource ('time-series observations for a FRED series ID') and a scope statement ('workhorse query for any economic indicator'). It is clear what it returns, but it does not distinguish itself from FRED siblings like fred_series_info, fred_search, or fred_quick_indicator, which share the FRED series-ID domain.

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?

The phrase 'workhorse query for any economic indicator' implies broad usage for pulling observations, but the description never states when to prefer this over fred_search (discovery) or fred_series_info (metadata). Usage is only implied, with no explicit alternatives or exclusions.

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