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

Annotations already declare readOnlyHint/openWorldHint, but the description adds much more: the result is a union of two sources with the source hidden per page, and the leadgen_tos_accepted tri-state is decoded (true/false/null) including exactly why null occurs (missing pages_show_list scope or no user access). The API-not-possible remediation note is directly actionable.

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: purpose and the page_id dependency come first, the per-page field semantics follow. The leadgen TOS passage is long but earns its place because those fields are what the call returns; a bulleted layout would improve scanability slightly.

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?

An output schema exists so return values needn't be explained, yet the description still decodes the two leadgen fields the agent will have to interpret. Combined with the permissions caveat and the consume-side rules, an agent has everything needed to call and act on the result.

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?

The single parameter has 0% schema description coverage, so the description must compensate, and it does: workspace is defined as the client workspace slug and marked optional when only one workspace exists. Only the exact slug format is left implicit.

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 ('Facebook-Pages, die für Anzeigen nutzbar sind') and immediately scopes it: the union of promote_pages and /me/accounts. It also names the downstream tools (meta_create_ad, lead tools) so an agent can place the tool in its workflow rather than guessing.

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 says the page_id is mandatory for meta_create_ad and that lead tools accept only account-assigned pages, which is a genuine when/when-not distinction. It even gives a diagnostic rule: if meta_create_ad rejects the page at step='creative', the page lacks the business/ad-account link.

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