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

No annotations, so the description carries the full load and does so well: it discloses the cost model ($0.02 via x402), the HTTP method/path, the composition of the result (liquidity-weighted blend, per-venue detail, divergence, 1h move), and the resolved-market terminal behavior (410 RESOLVED with outcome). Rate limits and auth beyond x402 aren't covered.

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?

A single dense paragraph that front-loads the core purpose before method, result shape, and operational details. Every clause carries information, though the trailing bracketed HTTP/price/docs block makes it slightly dense.

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?

No output schema exists, so the description appropriately describes the return shape (blend, per-venue detail, divergence, 1h move) and the resolved case. Combined with the sibling list and the search-pointer for slug discovery, an agent has what it needs, though error responses other than 410 aren't mentioned.

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?

With 0% schema coverage the description must compensate, and it largely does: it explains that the slug is a 'canonical market slug' discoverable via search, and that venue selection drives per-venue vs. blend output ('per-venue detail' alongside the liquidity-weighted blend). The exact slug pattern constraint is not restated, hence not a 5.

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+resource+scope: 'Blended event probability across Kalshi and Polymarket for one market.' This cleanly distinguishes it from probability_get-delayed (stale variant), probability_search (slug discovery), and probability_cross-venue-disagreement (aggregate view) without opening any 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?

Gives a concrete routing hint for obtaining inputs ('Find slugs via /v1/probability/search') and implies the one-market scope. It doesn't explicitly contrast with probability_odds-compare or probability_cross-venue-disagreement, so the when-not is left to inference.

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