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

Annotations already declare readOnlyHint and openWorldHint, and an output schema exists, so the safety and return-shape burden is largely offloaded. The description adds useful context about what the record contains (payoffs, beaten lengths, pedigree, odds), but no permission, latency, or historical-coverage behavior beyond the schema's 'from 2008-01-01' note.

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, contents listed first and the prerequisite/usage note second. The content enumeration is dense but relevant to selection; nothing is clearly wasted, though it could be trimmed.

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 annotations, a full output schema and 100% parameter coverage, the description supplies what an agent needs to pick and call it: purpose, contents, and where the keys come from. Minor gaps around historical limits and not-yet-run races remain but are not blocking.

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 baseline is 3, but the description adds workflow meaning by stating all three keys come from fanduel_racing_past_races. That tells the agent how to obtain valid values, which the schema alone does not.

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?

Specific verb (Get) + resource (one past FanDuel Racing race) with scope ('in full') and an enumeration of contents. Clearly the singular sibling of fanduel_racing_past_races, which is named in the description, so an agent can distinguish them without opening schemas.

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?

'Use it to review a result' gives the use context, and it explicitly states the source of the required keys (from fanduel_racing_past_races), routing the agent to the correct prerequisite tool. It does not state when not to use it or what happens for a race not yet run, so it stops short of full when/when-not coverage.

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