mcp-whatsapp

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

Annotations indicate destructiveHint=true and readOnlyHint=false, which is contradictory for a tool described as returning data. The description claims a read operation ('Return... as JSON') while annotations suggest destructive behavior. However, since the description doesn't explicitly contradict the annotations (it just describes functionality), and it adds value by specifying the JSON output format, it earns partial credit. No additional behavioral context like rate limits or authentication requirements is provided.

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 description is a single, efficient sentence that directly states the tool's function without unnecessary words. It's front-loaded with the core action and resource, making it easy to parse. Every word earns its place by specifying the output format ('as JSON').

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-parameter tool with no output schema, the description adequately covers the basic purpose. However, it lacks context about the return structure (e.g., what fields the JSON includes), potential errors, or how it interacts with other tools like 'unblock_contact'. Given the contradictory annotations (destructiveHint=true for a read tool), more clarity on behavior would improve completeness.

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?

With 0 parameters and 100% schema description coverage, the schema fully documents the input (none required). The description doesn't need to add parameter details, and it appropriately focuses on the tool's purpose. Baseline is 4 for zero-parameter tools when the schema coverage is complete.

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 clearly states the action ('Return') and resource ('user's current WhatsApp blocklist') with specific output format ('as JSON'). It distinguishes from siblings by focusing on blocklist retrieval rather than other WhatsApp operations like messaging or group management. However, it doesn't explicitly differentiate from potential similar tools like 'get_privacy_settings' which might also return user settings.

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 description provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., authentication state), when it's appropriate (e.g., checking blocked contacts before messaging), or what to do with the data. With many sibling tools available, this lack of contextual guidance is a significant gap.

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