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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description does add some return-shape context — that filteredEvents enumerates all filtered events in the window and that events rows carry filteredCount — but it never describes pagination behavior, aggregation granularity, or the overall response structure, which matters since no output schema exists.

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 short sentences, with the core purpose front-loaded before the return-detail caveat. The second sentence is compressed into semicolon-separated clauses and uses bare field names (filteredEvents, filteredCount) without framing, which makes it slightly harder to parse than it needs to be.

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 7-parameter read-only metrics tool with no output schema, the description covers purpose and two response fields but leaves the time-window semantics, pagination, and the full metric set unexplained. Annotations carry the safety story, but an agent still lacks enough to predict what it will get back.

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 71%, with start_time, failures_only, page_size, page_number, and destination_id already documented in the schema. The description adds nothing about event_type (undocumented in both places) or how page_size/page_number interact with the two enumerated result sets, so it does not compensate for the coverage gap.

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 names a specific verb and resource ('Get destination event-delivery metrics') and scopes it to success/failure rates, which distinguishes it from the source- and transformation-level metric siblings by the word 'destination'. It stops short of explicitly naming the nearest alternatives such as get_destination_latency_metrics or get_destinations_errors.

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?

There is no statement of when to pick this tool over get_destination_latency_metrics, get_destinations_errors, or get_live_events, and no prerequisites are given. Usage is only inferable from the tool name and the resource it mentions.

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