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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely new context by disclosing the credential-free public Gamma JSON source and enumerating that no user token, wallet signature, cookies, or account auth are required, which saves an agent from false auth assumptions.

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 core operation, then auth context, then a parameter gloss, then the alternative. The auth sentence lists four credentials, which is mildly verbose, but every sentence carries useful information for invocation.

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 an output schema present, return values need not be described, and annotations plus the auth disclosure cover the behavioral profile. A single-event detail getter is adequately specified, though it could signal what happens if the slug does not resolve.

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%, so the schema already documents both id and slug. The description restates slug with the same example ('world-cup-winner') present in the schema, adding no syntax or format detail beyond it, 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 ('Returns one normalized Polymarket event') and quantifies scope ('one'), which cleanly separates it from the sibling polymarket_events list tool. An agent can identify the operation 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?

Explicitly names the alternative: 'Use polymarket_events to list Polymarket events.' This routing signal is clear, though it stops short of stating the inverse condition (when to prefer this detail call over the sibling) and lists no other related detail siblings such as polymarket_market_detail.

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