upservice_create_external_message

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

Annotations already indicate readOnlyHint=false and destructiveHint=false. Description adds minimal behavioral context beyond stating it creates a message. Does not disclose required permissions, rate limits, or side effects. Does not contradict annotations.

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?

Description is front-loaded with the main purpose sentence and includes Args/Returns for structure. The Args section is redundant with the schema but not overly verbose. No unnecessary words.

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?

Missing details about the return value (only says 'JSON of the created message' without structure). No context about which external channel or how the message is routed. For a creation tool with output schema=true (though not provided here), more explanation is needed.

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?

Description lists subfields (content, message_id, mentions) but only minimally. Schema has 0% coverage for the top-level 'params' property, so description should provide more detail. However, the nested schema descriptions are rich, partially compensating. The description adds little semantic value beyond the schema.

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 'Create a new external/inbound message' with a specific verb and resource. The example 'from an external channel integration' adds context, but does not explicitly distinguish from sibling tools like upservice_send_channel_message or upservice_send_chat_message.

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?

Implies usage for external/inbound messages, but no explicit guidance on when to use this tool vs alternatives. No when-not-to-use or alternative tool names mentioned.

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