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

Beyond annotations, the description discloses important behavior: there is no dry run, the message is sent immediately, and push/e-mail notifications to agent addresses are deliberately not triggered. These are exactly the side-effect details an agent needs before invoking a non-idempotent write tool.

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?

The description is front-loaded with the action and key constraints, and it remains compact. There is some redundancy with the schema and the trailing EN keyword list adds little semantic value, but nothing is seriously bloated.

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 notification tool with annotations and no output schema, the description covers recipient, message length, immediate delivery, no dry run, own-address behavior, and the reading counterpart. Nothing essential for correct invocation 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 parameter documentation is already complete. The description mostly repeats the schema definitions for 'to' and 'text'; the only meaningful addition is that using one's own address for 'to' is allowed.

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: writing a user-to-user notification with handler 'user_message'. It also names the sibling tool that reads notifications, so the agent can distinguish sending from reading without opening the 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?

The description clearly establishes the sending context, says the recipient reads via ontouser_notification_index, and notes that sending to one's own address is allowed. It lacks an explicit when-not-use condition or a direct sending alternative, but the operational context is clear.

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