send_message

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

With no annotations provided, the description fully discloses critical behaviors: immediate sending (not a draft), E2EE handling ('fails honestly rather than sending plaintext'), per-call limitation ('One send per call'), and mention mechanics. This level of detail is essential for an AI agent to understand the tool's side effects and constraints.

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 dense with useful information, but every sentence serves a purpose—no fluff. It is slightly long but front-loaded with the core action and then details. Structured logically: main action, then E2EE, then mentions, then dependencies. Could be trimmed slightly but overall efficient.

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 and the set of sibling tools (31 tools including send_image, send_file, etc.), this description fully equips the agent. It addresses all relevant concerns: immediate sending, mentions prerequisites, E2EE safety, and how to obtain needed MIDs. No output schema is needed for this action.

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?

Although schema coverage is 100%, the description adds substantial meaning: it explains the relationship between the text parameter and mentions entries, specifies UTF-16 code units for offsets, and clarifies that replyToMessageId makes a quoted reply. It also instructs how to obtain MIDs for mentions, which is not in 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?

The description explicitly states 'Sends a text message to a LINE conversation immediately (not a draft)', uses a specific verb ('sends'), identifies the resource ('LINE conversation'), and distinguishes from related tools like send_image or send_file by focusing on text messages. It also clarifies behavioral nuances like E2EE and mentions, making the purpose unmistakable.

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 clear guidance on when to use: for immediate text messages. It explains prerequisites for mentions ('resolve MIDs via get_group_members or find_contact first') and correct usage ('put the visible "@name " into text AND pass a matching mentions entry'). It does not explicitly state when to avoid this tool, but the context of sending text versus other media is implied.

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