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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is well covered. The description adds that the tool returns metadata and can verify existence, but it does not disclose error behavior for nonexistent series, rate limits, or other operational quirks. With strong annotation coverage, a mid score is appropriate.

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 tight sentences with no filler. The first sentence states the action and the return payload; the second provides the use case. Everything earns its place and the most important information is front-loaded.

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 simple one-parameter, read-only lookup tool with rich annotations, the description is complete: it tells the agent what it does, what it returns, and when to use it. No output schema exists, but the description lists the return fields, so an agent can judge whether this tool satisfies the user's request.

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?

The input schema has 100% coverage: the only parameter, series_id, is described with helpful examples ('GDP', 'UNRATE', 'CPIAUCSL', 'DGS10'). The description adds little beyond confirming the ID identifies a FRED series, which the schema already conveys. Baseline 3 is correct because the schema carries the semantic weight.

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 states a specific verb ('Get metadata') with a specific resource ('FRED economic data series by ID') and enumerates precisely what is returned: title, units, frequency, seasonal adjustment, observation range, and notes. It clearly distinguishes this from pulling observations or searching for series, and the sibling context reinforces that fred_series_info is for metadata, not observations.

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 description explicitly says it is useful 'for verifying a series exists and understanding its measurement before pulling observations,' which gives clear usage context relative to fred_observations. It does not explicitly name alternative tools or state when not to use it, but the 'by ID' phrasing implies the series ID should already be known, and the connection to pulling observations is clear.

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