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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds useful behavioral context by naming the return fields and the closest-to-timestamp matching behavior, going beyond what annotations convey.

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 a single, well-structured sentence that front-loads the core purpose, then adds the optional behavior and return fields. No redundant or filler content is present.

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 tool with a full output schema and comprehensive parameter descriptions, the description is complete. It covers the main behavior, optional timestamp use, and the key returned values without needing to explain edge cases.

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%, so the input schema already documents both url and timestamp with examples and format. The description adds little beyond restating that the timestamp is optional and selects the closest snapshot, keeping it at the baseline.

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 uses a specific verb and resource: check whether a URL has an archived snapshot in the Wayback Machine. It clearly differentiates this from the related archiveorg.archive.search and archiveorg.archive.metadata tools by focusing on availability and returning the snapshot URL and capture timestamp.

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 the tool is for availability checks and optional timestamp-based lookup, but it does not explicitly state when to prefer this over sibling archive tools or when not to use it. Usage context is clear enough to infer, but no explicit alternatives or exclusions are provided.

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