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 covered. The description adds genuine context beyond them: an explicit statement that no community mutations are possible through MCP, and a prompt-injection warning that community names and descriptions are third-party content to be treated as data. It omits any mention of pagination behavior tied to the limit parameter.

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 tight sentences: the capability is front-loaded, followed by the read-only constraint and the injection warning. Every clause carries information an agent would otherwise lack, and there is no redundant restatement of the title.

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?

With an output schema present, return values need not be explained, and the tool's complexity is low (one optional parameter). The definition covers purpose, mutation limits and content-safety. The remaining gap is the absence of any guidance on the limit parameter or result truncation, which matters for a list operation.

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 0% and the single parameter (limit) has no textual description in the schema, only type, default 20, minimum 1 and maximum 50. The description says nothing about the limit, whether results are paginated, or what happens when more communities exist than the cap, so it does not compensate for the coverage gap. The structured bounds in the schema keep this at a minimum-viable 3 rather than lower.

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?

The description uses a specific verb and resource ("List the WhatsApp communities this account belongs to") and bounds the scope to the caller's own memberships. It does not, however, distinguish itself from near siblings such as list_groups or get_community, so an agent must infer the boundary between listing communities and listing groups or fetching a single community.

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?

The sentence "communities cannot be created, joined or changed via MCP" usefully rules out mutation attempts and implies this tool is the read path for community membership. There is no positive routing guidance telling the agent when to pick this over get_community (single-community detail) or list_groups (group chats), so usage is only implied.

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