fred_series_observations

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

Annotations declare readOnlyHint=true and openWorldHint=true. The description adds crucial behavioral details: missing values map to null not 0, error handling specifics (400 returns invalid_input with FRED message), pagination via hasMore/nextOffset, validation rules, and key placement. No contradiction with 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?

Well-organized with bold emphasis and bullet points for key sections. Front-loads core action and prerequisites. Slightly verbose but every sentence adds value; could be tightened slightly.

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?

Given 6 parameters, no output schema, and complex behavior (pagination, error handling, missing values), the description covers return format ({observations}), pagination metadata, error scenarios, and validation. Fully compensates for missing output schema.

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%, and the description enriches each parameter with examples (seriesId: 'GDP', 'CPIAUCSL'), default values (limit 100, max 100000), validation patterns, and additional context (startDate/endDate map to FRED observation_start/end). Goes beyond schema.

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 clearly states the tool fetches FRED series observations with specific verb 'Fetch' and resource 'FRED series' time series. It provides examples of series IDs and distinguishes from fred_search_series for discovery.

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?

Explicitly requires FRED_API_KEY with warning about no keyless tier, advises using fred_search_series for ID discovery, and lists optional parameters with defaults and constraints. Does not explicitly state when not to use, but context makes it clear this is the only FRED data-fetching tool among siblings.

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