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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: what each returned field means (plan tier, CMS connection state, relation, read-only status meaning 'frozen or ended billing'). It does not mention paging defaults, but the schema does.

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?

Front-loaded with the verb and resource, then the payload enumeration, then two short actionable sentences. The middle sentence is dense but every clause carries field information an agent cannot get from a missing output schema. Slightly long-winded but nothing is padding.

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 describe returns — and it enumerates plan tier, platform options, connection state, posts per week, relation with client email/clientId, and read-only status. Combined with the annotations covering safety and the schema covering parameters, an agent has everything needed to call this correctly.

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. The description earns the bump by explaining what the relation enum values actually mean operationally ('owner, invited, or partner client, with the client's email and clientId'), which is semantic detail the enum alone does not convey. limit and offset are left to the schema, appropriately.

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 ('List every site this credential can use on Blawgy') and immediately scopes it to the credential, which distinguishes it from create_site, get_overview and every other site-scoped sibling. It also flags itself as the entry point for the rest of the toolset.

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?

Gives concrete routing advice: 'Filter relation="partner_client" for client sites only' tells the agent when to apply a filter, and 'Use the `site` value from here in every other tool' tells it why this tool comes first. That is when-to-use plus downstream dependency, which is unusually explicit.

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