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

Annotations already declare read-only and idempotent. Description adds specific behavioral traits: returns top 12 probabilities for multiple-choice, includes plain-text description, creator, volume, liquidity, resolution. Also notes 'Keyless' (no API key needed). No contradiction.

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 sentences, each adding value. Front-loaded with the core action. No filler words. Highly efficient.

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 simple retrieval tool with no output schema, the description covers all necessary aspects: purpose, parameter usage, response behavior, and key fields. No gaps.

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% with descriptions. Description adds critical semantic: 'Provide exactly one of slug/id', making the mutual exclusivity and requirement explicit beyond the schema.

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?

Clearly states verb ('get'), resource ('full detail for a single Manifold market'), and identification method ('by its URL slug or id'). Distinguishes from sibling tools like search_markets by specifying 'single' and the exact identifiers.

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 constraint: 'Provide exactly one of slug/id.' Although it doesn't contrast with alternatives, the context of retrieving a single market by identifier is self-explanatory.

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