send_chat_message

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

Annotations already declare readOnlyHint=false and idempotentHint=false, but the description adds concrete consequences beyond that: the message is delivered externally, cannot be recalled by this server, and repeated calls produce duplicates. It also discloses a specific failure path (error when the lead has no conversation), which the annotations do not convey.

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?

Three short sentences, front-loaded with the core action, then the lookup rule, the safety implications, and the alternative. Every sentence earns its place and no padding is present.

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?

With no output schema, the description carries the right information: what it does, what requirement must hold, what side effects occur, and which sibling to use instead. Nothing an agent needs to invoke this correctly is missing.

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 100%, so both parameters are already documented in the schema, including that lead_id must come from list_leads. The description adds only indirect context ('first conversation linked to the lead'), not new per-parameter meaning, so the baseline 3 applies.

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 a specific verb and resource ('Send an outgoing chat message to the customer in a lead's conversation') and immediately distinguishes itself from the sibling add_note. An agent can tell this apart from internal note-taking tools without opening any schema.

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?

Explicitly routes the agent: use this for outgoing customer-facing messages, use add_note for internal notes. It also names the precondition (the lead must already have a linked conversation) and the failure mode when that precondition is unmet.

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