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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint: false, and openWorldHint: false. The description adds valuable context beyond annotations: it requires a FRED_API_KEY environment variable and describes the return format (date + value pairs with metadata). It does not cover rate limits or error behavior, but the added auth and return info make it more than adequate.

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?

The description is well-structured with a clear front-loaded purpose, a bulleted usage list, and parameter hints. It is appropriately sized for a tool with many optional parameters, though slightly verbose in the usage bullet list.

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?

An output schema exists, so detailed return value documentation is not strictly needed, yet the description still summarizes the return format. It covers core usage, authentication, and source, but the unexplained optional parameters (e.g., wholesaler_ids, mcp_prompt_id) reduce completeness for an agent that might need to supply them.

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 reported as 0%, so the description must carry parameter meaning. It mentions observation_start/observation_end, frequency, and implies series_id, but omits limit, source_resource_id, mcp_prompt_id, question_asked, wholesaler_ids, exclude_fillers, additional_display_fields, and optional_additional_filters. The majority of nested parameters are left unexplained, leaving an agent without guidance on how to use them.

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 ('Fetch') and resource ('time-series observation data from FRED for a specific economic series'), and explicitly distinguishes itself from the sibling SearchFredSeries by saying to use that first if the series ID is unknown.

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?

Provides an explicit 'Use this tool when' list with four clear scenarios, and names the alternative tool (SearchFredSeries) for when the series ID is not known. This fully covers when to use this tool versus alternatives.

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