get_direct_chat_by_contact

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

No annotations are provided, so the description carries the burden; the verb 'Get' does imply a read-only lookup and 'chat metadata' hints at the return shape. It does not say what happens when no chat exists for the number, whether the match is exact, or whether any auth scope is required.

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?

Short and front-loaded, with the key operation in the first clause. The 'Args:' block is boilerplate that adds nothing over the schema but is not harmful.

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 need not be explained, and a single-parameter read tool is inherently simple. Still, the one thing an agent could get wrong, the phone number format, is left unspecified.

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%, so the description must compensate and it largely restates the field name ('The phone number to search for'). It never specifies the expected format (country code, E.164, digits only), which is the key ambiguity for a phone-number lookup.

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 WhatsApp chat metadata') and scopes it by sender phone number, which distinguishes it from the broader list_chats and the id-based get_chat. It stops short of naming those siblings explicitly.

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?

There is no guidance on when to use this versus list_chats, search_contacts, or get_chat, and no prerequisites or failure conditions are mentioned. The agent must infer from the name that this is the lookup-by-phone-number route.

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