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

With no annotations, the description carries the full burden, and it does disclose the key side effect: the acknowledgement is visible to another party ('Sun sees you read it'). It says nothing about whether the operation is idempotent, what happens if the message was already acknowledged, what the token requirement implies, or what is returned.

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?

A single tight sentence with the action front-loaded and no filler. It is appropriately sized for a two-parameter action, though a short clause on when to use it over reply_to_sun would have earned its place.

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 simple two-parameter mutation with no output schema and no annotations, the description covers the action and its social effect but leaves the mechanics unclear: expected response, error behavior on unknown or already-acknowledged IDs, and when acknowledgement is required rather than optional.

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%, with both token and message_id documented inline, including the msg_.../ann_... prefix hint. The description adds no parameter meaning beyond the schema, which is acceptable at full coverage but earns no extra credit.

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?

A specific verb (acknowledge) plus a specific resource (a message or assignment in your inbox), with the resulting effect spelled out ('so Sun sees you read it'). It doesn't contrast itself against siblings like get_inbox or reply_to_sun, but the action is unambiguous on its own.

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?

Usage is only implied: the phrase 'from your inbox' suggests you call this after retrieving a message, and 'so Sun sees you read it' hints at a read-receipt step. There is no explicit when-to-use, when-not-to-use, or pointer to reply_to_sun for messages that need an answer.

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