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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds two genuinely useful things beyond that: the required auth scope and a warning that human-written text appears in untrusted_fields and must never be treated as instructions. It still says nothing about what 'free' means operationally (taken vs. invalid vs. reserved).

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 short sentences with the purpose front-loaded and no filler. The untrusted_fields clause is slightly generic but earns its place as a security instruction.

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 one-parameter read tool with rich annotations and no output schema, this is close to sufficient, but it leaves the sole parameter undefined and does not describe possible outcomes (free, taken, invalid), which an agent needs to interpret the result.

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?

There is one parameter with 0% schema description coverage, and the description never explains what 'subdomain' denotes, its format, or how it relates to the DJ link being checked. With the schema bare, the description needed to carry this meaning and does not.

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 states a specific verb and resource ('Check whether a DJ link is free'), so an agent can tell it is an availability probe rather than a mutation. It does not, however, contrast itself with the closely related siblings claim_dj_link, release_dj_link, or check_handle, so the distinction has to be inferred from the tool name.

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 only guidance is the permission requirement 'Needs `profile:read`', which is a prerequisite rather than a when-to-use rule. Nothing says when to call this vs. check_handle or claim_dj_link, nor what to do when the link is not free.

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