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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context — that a group marked `locked` cannot be posted to, and that `id` values from this result are the inputs to create_post — but it does not describe the overall response shape or ordering. The trailing 'Read only' merely restates the annotation.

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?

The purpose and the 'call this first' directive are front-loaded, and each sentence except one adds routing or constraint information. The final 'Read only.' is pure duplication of readOnlyHint and does not earn its place.

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?

There is no output schema, so the description must convey the return content; it does so adequately by stating that groups are returned with their accounts and by surfacing the `locked` flag and the usable account `id`. Pagination or response envelope details are absent, but for a small closed-world lookup 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 description coverage is 100%, and the schema already documents that `social_group` accepts a name (any case) or an id and should be omitted to list everything. The description's 'Give `social_group` to see just one group' is essentially redundant. Baseline 3 applies when the schema carries the semantics.

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 and resource ('Lists the social groups ... and the accounts in each') and even defines the domain term ('a social group is one brand: its own set of social accounts'). An agent can distinguish it from get_brand, list_media, and list_posts without opening the schema.

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?

Explicit ordering ('Call this first, before posting') plus a concrete routing rule: find the brand's social group here, then pass the account `id` to create_post. It also names the filtering condition for the optional parameter, leaving nothing to inference.

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