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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered structurally. The description adds no behavior beyond that — no message ordering, no pagination/cursor behavior, no note that history may be truncated to recent messages, and no hint about what each message entry contains.

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 short sentences, front-loaded with the operation, with zero filler. The second sentence duplicates schema content, which slightly weakens its value but does not bloat the definition.

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 3 flat parameters and rich annotations, the description is minimally adequate. But with no output schema, the agent gets no information about return shape, message ordering, or whether history is complete or windowed — the main open question for a history-fetching tool.

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 schema already documents instance_id, chat_id formats, and the count default/max. The description's 'default 50, max 100' merely restates the schema, adding no new semantics. Baseline 3 is correct.

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: 'Get chat message history.' An agent knows exactly what it retrieves. However, it does not distinguish itself from close siblings like whatsapp_read_chat, whatsapp_get_message, or whatsapp_last_incoming_messages, so the differentiation bar for a 5 is not met.

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 only guidance concerns response size ('use a small count'), which is parameter tuning, not when-to-use. There is no statement of when this is preferable to whatsapp_read_chat or the last_incoming/last_outgoing siblings, and no prerequisites such as needing a connected instance.

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