Inspect a UUID / ULID

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

Annotations already declare readOnlyHint, idempotentHint, and closed-world, so the safety profile is covered; the description adds genuine context on accepted input tolerance (braces, urn:uuid:, missing dashes) and which versions carry embedded timestamps. It stops short of saying what the output looks like for an invalid string (error vs. a valid=false flag), which is the one behavior an agent still has to guess.

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 tightly written sentences front-load the core purpose and the accepted-format caveat. The trailing marketing URL for the web version does not help an agent decide or invoke, so it is mildly extraneous.

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 no output schema, the description carries the return-value burden and does so reasonably, naming the reported fields and the conditional timestamp behavior. The main shortfall is the unspecified invalid-input response, which leaves an agent without a full picture of outcomes.

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?

The single parameter is fully documented in the schema, so baseline is 3, but the description adds real meaning beyond it by specifying which input format variants the 'id' value may take. That extra disambiguation is directly useful for constructing a valid call.

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?

States a specific verb+resource pair ('Check whether a string is a valid UUID ... or ULID') and enumerates what is reported: version, variant, canonical form, and embedded creation time. This is clearly distinguishable from the generation sibling id_generate, since the tool only inspects an existing string.

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?

Usage is implied by the phrasing ('check whether a string is valid'), but there is no explicit when-to-use statement, no exclusion, and no named alternative such as id_generate for producing new identifiers. The agent must infer the boundary from the tool name and description alone.

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