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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint. The description adds valuable context beyond that: persisted impact_direction and reason, not-found behavior, and disclaimers about no account access, no order placement, and not being investment advice. No contradiction with annotations.

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?

Description is compact, front-loaded with the core purpose ('Full detail for one event_id only'), and every sentence adds necessary context: scoping, alternative, error behavior, and safety disclaimers. No redundancy or filler.

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 read tool with an existing output schema, the description covers purpose, usage, error handling, and safety. It doesn't explicitly route to other siblings (like explain_market_move) but that's not critical given the clear event_id context. Overall adequate and complete for correct invocation.

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 already fully documents the event_id parameter (100% coverage) with details like 'opaque digest id, not a trading pair slug'. The description only reinforces that the ID comes from get_latest_events, adding marginal meaning beyond the schema. Baseline 3 is appropriate.

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?

Description clearly states the tool returns 'Full detail for one event_id only' and explicitly contrasts with get_latest_events ('Filtered event list or timeline -> get_latest_events'). This distinguishes it from the primary sibling while naming the exact resource and operation.

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 guidance: use get_latest_events for filtered lists/timelines, and implies this tool is for full detail on a specific event_id. Mentions 'Unknown id returns not found' which sets expectations. Does not exhaustively list all sibling alternatives, but the main one is covered clearly.

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