on_this_day

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

Annotations already indicate read-only, non-destructive, and closed-world behavior. The description adds valuable context beyond this: it explains the default filtering logic (excludes contacts never replied to), the temporal scope (1, 2, 3+ years ago), and the nostalgic purpose. No contradictions with annotations exist.

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?

The description is front-loaded with the core purpose in the first sentence, followed by clarifying details. Every sentence adds value: the analogy, temporal scope, and default behavior. It is efficiently written with zero redundant information.

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?

Given the tool's moderate complexity, rich annotations, and full schema coverage, the description is nearly complete. It explains the tool's unique purpose and behavioral context well. The main gap is the lack of an output schema, but the description compensates by implying the return type (messages).

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%, providing full parameter documentation. The description does not add specific parameter semantics beyond what the schema already states. It mentions filtering by contact and the include_all option implicitly, but no new syntax or format details are introduced.

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 clearly states the tool's purpose: retrieving messages from this date in previous years, analogous to 'Memories' for iMessage. It specifies the scope (messages from you and your contacts) and distinguishes it from siblings by focusing on historical date-based retrieval rather than searching, stats, or contact management.

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 provides clear context for when to use this tool: for nostalgic or reflective purposes looking at past conversations. It mentions a default exclusion (contacts never replied to) and an option to override this. However, it does not explicitly state when NOT to use it or name specific alternatives among siblings.

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