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

Annotations already declare the write profile (readOnlyHint=false, idempotentHint=false, openWorldHint=true, non-destructive). The description contributes the useful extra context that the recipient is a human and that the agent speaks as the customer, but says nothing about delivery behavior, whether the expert is online, or what the call returns.

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?

Two short sentences, no redundancy, with the action stated before the role clarification. Every sentence carries information an agent needs.

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?

For a two-parameter write tool with full annotation coverage and no output schema, this is nearly complete. The role framing is the essential missing piece most definitions omit, though it could note that expert replies must be fetched via read_messages.

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%, with both message and session_id already documented including the session_id provenance. The description only reinforces the active-session constraint, 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 ('Send') and resource ('a chat message to the human expert'), scoped to an active session. The role framing ('You are the customer in this conversation') cleanly separates it from read_messages and from the session-management siblings.

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 the precondition clearly ('in an active session'), which pairs with the session_id sourced from hire_human_expert. It stops short of naming read_messages as the retrieval counterpart or stating what to do when no session is active.

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