tool_send_message

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the tool sends messages but doesn't cover critical aspects like whether it requires authentication, potential rate limits, error conditions (e.g., invalid recipient), or what happens on success/failure. The description adds some context about recipient formats but misses key behavioral traits needed for safe invocation.

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 appropriately sized and front-loaded with the core purpose in the first sentence. The parameter explanations are organized in a clear list format, making it easy to scan. While efficient, it could be slightly more concise by integrating the parameter details more seamlessly, but overall it avoids unnecessary verbosity.

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 complexity of a message-sending tool with 3 parameters, 0% schema coverage, no annotations, and no output schema, the description is moderately complete. It covers parameter semantics well but lacks behavioral context (e.g., side effects, errors) and output information. For a tool that performs a write operation, more completeness around success criteria and potential impacts would be beneficial.

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?

The schema description coverage is 0%, so the description must compensate. It provides meaningful semantics for all three parameters: 'recipient' explains formats (phone, email, contact name, 'contact:N'), 'message' clarifies it's text to send, and 'group_chat' indicates it uses chat ID instead of buddy. This adds substantial value beyond the bare schema, though it could include examples for the message parameter or more details on group_chat behavior.

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 ('Send a message') and resource ('using the Messages app'), making the purpose immediately understandable. It distinguishes itself from sibling tools like tool_fuzzy_search_messages or tool_get_recent_messages by focusing on sending rather than retrieving messages. However, it doesn't explicitly differentiate from potential message-related tools that might exist elsewhere.

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 implies usage through the parameter explanations (e.g., 'contact:N' for selecting from matches), suggesting when to use certain recipient formats. However, it lacks explicit guidance on when to use this tool versus alternatives like tool_get_chats for viewing chats or tool_find_contact for contact lookup, and doesn't mention prerequisites such as needing the Messages app available.

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