wa_read_messages

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds one genuinely useful behavioral clue — reads happen 'via Firefox Bridge', implying a browser must be running — but says nothing about what happens if the bridge is unavailable or whether reads are rate-limited.

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?

A single front-loaded sentence with no filler. It is arguably too terse for a tool with an external dependency, but nothing is wasted.

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 only two fully described parameters and a simple read operation, the description covers what the agent needs to invoke it. The missing piece is the shape of a returned message (sender, timestamp, text), which matters since there is no output schema.

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%, documenting both 'chat' (substring match) and 'count' (default 10). The description's 'last N messages' and 'chat' echo the schema without adding format or syntax detail, so baseline 3 applies.

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 (read) and resource (last N messages from a WhatsApp chat), which is clear enough to separate it from wa_send_message and wa_list_chats. It doesn't explicitly name those siblings as alternatives, but the operation is unambiguous.

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?

No guidance on when to use this versus wa_list_chats (to discover a chat name) or wa_send_message. The dependency on Firefox Bridge is mentioned but not framed as a prerequisite or failure condition.

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