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

Annotations only declare destructiveHint=true/readOnlyHint=false; the description adds real behavioral context beyond that: counting is per-device not per-view, the floor is 3 opens, already-admitted visitors are not revoked, and null removes the limit. These are non-obvious operational traits an agent could not infer from the schema.

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?

Dense but front-loaded: the core effect comes first, then the counting caveat, then the applicability limits. Every clause carries information, though the parenthetical device-counting example lengthens the sentence more than strictly necessary.

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 3-parameter mutation tool with no output schema, the description supplies scope, counting semantics, minimums, and the sibling alternative, so nothing an agent needs to invoke it correctly is missing.

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 adds meaning the schema lacks: why max_opens cannot go below 3 (device counting) and what a null value means. reset_counter is only explained by the schema, so it is not a full 5.

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 action (limit opens), the resource (gated site), and the exact effect (after N logins the link stops working). It also differentiates itself from siblings by naming set_site_members_access and the access models it does not apply to.

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?

Explicitly scopes applicability to password, email_list and subscribers access, and routes members/paywall cases to set_site_members_access with max_seats. It also states the minimum (3) and that existing visitors keep access, so an agent knows both when and when not to call it.

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