Fair line

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

Annotations already establish read-only, idempotent, closed-world, non-destructive behavior, so the bar is lower; the description still adds real context by disclosing that output is a synthesized line with per-source weights and freshness plus fee-adjusted edges, and by warning that confidence and singleSource must be checked before acting. It does not cover rate limits or failure modes, keeping it below 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, purpose first, caution second — well front-loaded with no wasted preamble. The first sentence is dense with a long parenthetical enumeration, but every listed element is meaningful output information.

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 with an output schema and full annotations, the description covers what the tool produces, the derived nature of the data, and the caveat about confidence/singleSource. What remains missing is when to pick it over its siblings, which is the one gap an agent could trip on.

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?

Only one parameter, and the schema documents it at 100% coverage ('Outcome id'). The description calls it 'one market's fair line', which introduces a mild market-vs-outcome ambiguity rather than clarifying the parameter, so the baseline 3 applies.

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 ('Gives one market's fair line') and enumerates what the result contains: probability and band, method, confidence, sources with weights and ages, top of book, and fee-adjusted edge. The 'one market' scope implicitly separates it from the multi-market siblings (odds_markets, odds_cluster), but no sibling is named explicitly.

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 second sentence gives useful downstream guidance ('Check confidence and singleSource before acting on the line'), which tells the agent how to consume the result. It does not say when to choose this tool over odds_markets, odds_cluster, or odds_new, nor any preconditions, so selection guidance is only implied.

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