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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description adds the non-obvious error behavior for invalid slugs, which is real value beyond structured fields. The listing of returned fields is somewhat redundant with the output schema, keeping it short of a 5.

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 sentences, zero filler, with the capability statement first and the dependency/error caveat second. Every clause carries information the agent can act on.

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 single-parameter read tool with an output schema and safety annotations, the description covers what it returns, where the input comes from, and what happens on a bad input. Nothing an agent needs in order to invoke it correctly is missing.

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 baseline is 3, but the description adds provenance information the schema does not: the slug must come from fanduel_research_authors, and invalid values error rather than silently returning empty. That meaningfully narrows the acceptable input space.

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 and resource ('Get one FanDuel Research author's details') and enumerates the returned content (bio, images, social accounts, sports/topics). It is clearly distinguishable from the sibling list tool fanduel_research_authors, which only yields slugs.

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 tells the agent to pair it with an author slug obtained from fanduel_research_authors, which is the correct upstream call. It also names the failure mode ('an unknown slug returns an error'), so the agent knows what to do if lookup fails.

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