zulip

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

With no annotations provided, the description carries full burden for behavioral disclosure. It states this sends messages but doesn't mention permissions required, rate limits, whether messages are editable/deletable after sending, or what happens with invalid recipients. The description is minimal and lacks important operational context.

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 efficiently structured with a clear purpose statement followed by parameter explanations. Every sentence adds value, and there's no redundant information. The two-sentence format with parameter details is appropriately concise.

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?

Given the tool has an output schema (which handles return values) and only 2 parameters with basic types, the description provides adequate context for a simple messaging tool. However, as a mutation tool with no annotations, it should ideally mention more about behavioral aspects like permissions or error handling to be fully complete.

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%, but the description adds basic semantics for both parameters: 'recipients' as email addresses in a list and 'content' supporting Zulip markdown. This compensates somewhat for the schema gap, though it doesn't provide format examples beyond the basic array structure or explain markdown limitations.

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 verb ('Send') and resource ('direct message to one or more users'), making the purpose unambiguous. However, it doesn't explicitly differentiate from the sibling 'send_message' tool, which might handle different message types like stream messages.

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 like 'send_message' or 'reply'. It mentions sending to 'one or more users' but doesn't clarify if this is for private conversations only or how it differs from other messaging tools in the sibling list.

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