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

Annotations already cover read-only, idempotent, non-destructive, and open-world behavior, so the description only needs to add non-obvious behavior. It discloses the exact return shape as a list of { year, month, day, event } and shows a sample call, which meaningfully extends the structured metadata.

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 sentences carry all essential information with the primary purpose front-loaded, followed by filter behavior, output shape, and a compact example. No filler or repeated schema text.

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 simple read-only lookup with no required parameters, the description covers input options, output structure, and a usage example. It does not state default behavior when no parameters are supplied, but the open-world and read-only annotations plus schema make the tool safely callable without that detail.

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 100%, but the description adds the relationship between parameters ('free-text keyword and/or an exact date') and demonstrates it with an example call. This clarifies combinational semantics beyond what individual parameter descriptions provide.

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 opens with 'notable events from world history' and specifies the core operations: filter by keyword and/or exact date, returning a list of event records. This is clear and unambiguous, though it doesn't call out any sibling tool for differentiation.

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 implies when to use the tool—whenever a historical event lookup with keyword/date filtering is needed—and provides a concrete invocation example. It doesn't explicitly contrast with alternatives or state conditions where another tool should be preferred, so guidance is implied rather than explicit.

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