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

Annotations already declare readOnlyHint and idempotentHint, but the description adds valuable context: 'Cheaper and faster' performance expectations and the 'not-found error' behavior. It also clarifies the lightweight nature and what fields are included, exceeding the structured metadata's coverage.

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?

Two sentences, front-loaded with the main purpose, followed by usage and error info. Every sentence adds distinct value with no redundancy, making it 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 single-parameter tool with output schema and strong annotations, the description covers purpose, usage, alternatives, and error behavior. It is complete and self-contained for an agent to correctly invoke the tool.

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?

The schema provides 100% coverage for the single parameter event_id with a clear origin ('from list_events, query_events, or search results'). The description adds no new parameter-level semantics beyond what the schema already states, so the baseline of 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 uses a specific verb ('Get a lightweight live score snapshot') with a clear resource ('an event') and enumerates exact contents (status, period, clock, scores, last-updated). It also distinguishes from sibling get_event by highlighting the scope difference, making its purpose unambiguous.

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?

The description explicitly states when to use this tool instead of get_event ('when you only need the score, not participants or venue') and notes the error condition for a non-existent event_id. This provides clear decision guidance relative to alternatives.

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