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

Annotations already cover readOnly/openWorld/idempotent/non-destructive, so the bar is lower, and the description still adds real behavior: share links are resolved on Moda's servers, and the result includes a third state 'could_not_check'. It also pre-empts the missing output schema by naming the verdict values, the group name on success, and the pass-along sentence. It doesn't say whether private/restricted groups or post links affect the verdict.

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?

It leads with the usage condition, then the parameter, then the return contract — a sensible front-loaded order with no filler. The mid-text 'link:' fragment reads as a slight formatting seam rather than a sentence, but nothing is redundant.

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 contract and does so adequately: enum-like verdicts, conditional group name, and a human-facing sentence. The only gap is guidance on what an agent should do after a 'could_not_check' result, but for a single-parameter check tool this is close to complete.

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%, so the baseline is 3, but the description goes further by distinguishing accepted link shapes (facebook.com/groups/... versus facebook.com/share/...) and explaining that share links are resolved server-side to find the target group. That is meaning the schema's one-line 'group, post or share link' does not convey.

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 names a specific verb (check) and resource (a Facebook group/post link) and states the exact question answered: whether the group is an official Moda group. That outcome framing separates it cleanly from siblings like find_moda_groups (search) and check_moda_contact (contact validation) without needing to name them.

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?

It gives a concrete trigger — 'Use when someone has a link ... and wants to know whether that group is an official Moda group' — which is enough for an agent to route correctly. It does not state exclusions or explicitly point to alternatives such as find_moda_groups for when no link exists, so it stops short of a 5.

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