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's '[read-only]' marker duplicates that, and the endpoint wrapper adds minor context, but nothing about pagination, ordering, or result size is disclosed. With annotations doing the heavy lifting, 3 is appropriate.

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 compact sentences; the semantic definition of a share rule is front-loaded ahead of the endpoint wrapper. No filler, though the endpoint citation is the least valuable element and could be dropped.

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 zero-required-param list tool with no output schema, the description gives the agent enough to know what comes back conceptually (rule conditions plus approval mode). It could mention ordering or whether all rules for the brand are returned, but the gap is small.

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% for the single brandId parameter, and the schema already explains the 'personal' key, omitted-value default, and brand-bound behavior. The description adds nothing about brandId, so the baseline 3 is correct.

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 and goes further by defining what a share rule actually is (publish → reshare/comment after N minutes with text T, plus approval mode). That domain definition helps distinguish it from siblings like list_attribution_rules and create_share_rule. It doesn't explicitly name a sibling, so it lands at 4 rather than 5.

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?

There is no when-to-use or when-not-to-use guidance, no prerequisites, and no pointer to create_share_rule for the write counterpart. The '[read-only]' tag and the GET endpoint hint that this is a viewing operation, but the agent must infer that entirely.

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