send_message

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

Discloses E2EE behavior: 'Always E2EE (pairwise for 1:1, group key for group/room); fails honestly rather than sending plaintext if the key cannot be resolved.' Also clarifies mention behavior: without mentions array, @name is plain text. No annotations were provided, so description carries full burden.

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?

Single paragraph with four concise sentences. Front-loaded with main purpose. Every sentence adds value; no redundancy.

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?

Covers main behavior, mentions, E2EE, and required MID resolution. Lacks mention of any text length limits or rate limits, but the tool is straightforward. With no output schema, the description adequately describes what happens.

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 coverage is 100% (all parameters documented). Description adds context: chatId references list_conversations, replyToMessageId references get_chat_messages, and explains the interaction between text and mentions. This enhances understanding beyond schema alone.

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?

Description clearly states 'Sends a text message to a LINE conversation immediately (not a draft).' This is a specific verb+resource combination that distinguishes from sibling tools that send other content types (e.g., send_image, send_sticker). No ambiguity.

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?

Provides explicit guidance on when to use mentions and how to resolve MIDs via sibling tools (get_group_members, find_contact). Also notes that each call sends exactly one message. However, it does not give when-not-to-use alternatives like other send tools, or mention rate limits.

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