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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety need not be re-explained. The description adds meaningful context beyond that: the Polymarket-primary/Manifold-fallback sourcing behavior and an errors field indicating partial failures. It does not discuss rate limits or data-freshness/caching behind the word 'live', which keeps 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?

Three labeled segments (purpose, when/when-not, returns) with zero filler and the core purpose front-loaded. The longer returns block earns its space because no output schema exists.

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 supplies the return shape including nested markets/outcomes and the errors field, plus source fallback behavior. Everything needed to decide to call it and interpret results is present for a 2-parameter read-only lookup.

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 50%: 'query' is documented in the schema itself, but 'limit' has only type/bounds/default with no explanation of what it caps. The description's return shape hints at query and count but never explains the limit parameter or how the two interact. Baseline 3 is appropriate when the schema carries roughly half the load.

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 concrete resource ('live implied probabilities from prediction markets') with named upstream sources (Polymarket primary, Manifold fallback). It also distinguishes itself from siblings crypto_trending and attention_trend by name, so an agent can route without inspecting other 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?

Provides explicit when-to-use phrasing ('what does the market think will happen', election/crypto/macro probabilities) and explicit do-not-use cases that point to the correct alternatives. Both the positive and negative selection conditions are stated.

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