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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, yet the description still adds a lot: free-tier status (an access/cost constraint), the scoring methodology (de-vig + Brier vs. result and vs. other books), and the meaning of each emitted field including the skill_bp sign convention and the verdict enum values. It also sets an explicit expectation boundary by denying any betting-edge interpretation.

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?

Front-loaded with the free-tier flag and purpose, then the methodology, then the field list and use cases. The metric enumeration is long but earns its place since there is no output schema; only minor tightening is possible.

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 takes on the return-value burden and does so thoroughly, enumerating per-book fields plus by_sport and by_market breakdowns. Both optional parameters are fully documented in the schema, so nothing needed to call this 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 description coverage is 100% – both parameters carry ranges, defaults and examples in the schema itself. The description adds no syntax, format or semantics for 'days' or 'sport', 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?

The description names a specific verb+resource ('How well each sportsbook prices player props') and immediately scopes it to a de-vigged Brier scoring report, which cleanly separates it from sibling tools like propline_get_best_line or propline_get_event_ev. An agent can tell what this 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 two concrete selecting questions ('which book prices props most accurately', 'which book has the lowest margin') and flags that this is a pricing report, never a profit claim or betting edge, which implicitly routes agents away from EV/edge tools. It does not name an explicit alternative sibling or state when NOT to use it, so it stops short of a 5.

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