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

Annotations only cover the safety profile (readOnly false, destructive false, openWorld false). The description adds genuinely useful behavior an agent cannot get from annotations: the note is never sent to the customer, does not pause the bot, and surfaces in the inbox and in get_conversation. It stops short of stating permissions or return shape, so 4 rather than 5.

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 sentences, zero filler, with the essential scope constraint ('private', 'NEVER sent to the customer') front-loaded ahead of the alternative-tool pointer.

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 five-parameter mutation tool with no output schema, the description covers the critical unknowns: audience (internal only), side effects on the bot, and visibility surface. It could say more about where the note is readable programmatically, but nothing an agent needs to call it correctly is absent.

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 80% and the schema already documents note, platform, accountId, and idempotencyKey. The description adds nothing about parameters, and conversationId is left undocumented in both places. Baseline 3 is appropriate where the schema carries the load.

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 states a specific verb and resource ('Leave a private note on a conversation') and immediately delimits its scope as team-internal. It is unmistakably distinct from reply-oriented siblings like send_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?

It supplies both when-to-use (team context, what was promised, what to check) and an explicit when-not with a named alternative: 'To answer the customer use send_message instead.' No inference is required to route between the two.

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