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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile needs no restating. The description adds useful domain framing (what an event is) but says nothing about behavior on a missing ID or what the response contains.

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 short sentences, front-loaded with the action and followed by domain context and an ID example. The third sentence overlaps with the schema's own format note, so it is slightly redundant but not wasteful.

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 one required parameter and full schema coverage, the input side is well covered. Since no output schema exists, the description would need to explain return values or not-found behavior, and it does neither, leaving a meaningful gap for a lookup 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?

Schema description coverage is 100% and the schema already documents the single 'id' parameter including its 'number-timestamp' format. The description repeats that format and adds one concrete example, which is marginal added value beyond the schema rather than new semantics.

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 gives a specific verb+resource ('Gets a budget event by its ID') and explains that events are recurring or one-off income/expense entries used in forecasting. 'By its ID' implicitly distinguishes it from list_events, but no sibling is named, so it falls just short of the top score.

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?

Retrieval-by-ID is implied by 'by its ID', which suggests use when you already have an identifier rather than when browsing. However, it never states when to prefer this over list_events, nor what to do when the ID is unknown, leaving usage to inference.

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