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

Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the safety profile is covered. The description adds genuine behavioral value by enumerating the returned metrics (total receipts, disbursements, individual contributions, cash on hand, debts), which tells the agent what data it will get. It stops short of return format or pagination/cap 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 tight sentences with no waste: purpose first, returned contents second, and the cycle-filtering hint last. It is front-loaded and every sentence earns its place.

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 usefully enumerates the returned fields and the annotations carry the safety profile, so an agent has what it needs to call it. It omits minor details like the default limit of 10 and that no cycle returns all cycles, but these are documented in the 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%, so the schema itself documents candidate_id, cycle, and limit with examples and defaults. The description only reiterates the cycle filter and adds no syntax or format detail beyond the schema. Baseline 3 is appropriate here.

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 and resource ('Get aggregate campaign finance totals for a candidate by FEC candidate_id') and explicitly frames it as cycle-broken-down aggregates. This clearly separates it from siblings like fec_candidate_details (profile data) or fec_candidate_search (finding candidates). An agent can tell what it returns without opening the schema.

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?

It gives one concrete usage hint ('Filter to one cycle with the cycle parameter') but offers no when-to-use/when-not guidance and never names an alternative such as fec_candidate_details. Usage is implied rather than spelled out for the agent deciding between FEC tools.

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