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

With annotations declaring it non-readOnly and non-destructive, the description adds real behavioral context: the note surfaces the next time the friend asks for their notes, the content must be in the sender's own words, and the target must already be a friend. It does not state whether repeat sends accumulate separate notes (idempotentHint=false), which would be useful for a messaging-style write.

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, front-loaded with the action and delivery behavior, then the usage condition, then the sibling fallbacks. No redundant restatement of the title or schema.

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?

No output schema exists, but the description covers what happens after the call (friend sees it on their next notes request) and the precondition on the recipient. Missing only the non-idempotent behavior, which is the one open question an agent would have before sending twice.

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%, so the baseline is 3, but the description adds a constraint not present in the schema: 'to' must be an existing friend handle (not merely any string, as the schema's maxLength-40 string implies), routing agents to add_friend/invite_friend otherwise.

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 ('Leave an Oyeh note for a friend's AI assistant') and immediately describes the delivery mechanism, which distinguishes it from the read-oriented check_notes sibling in the same family.

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?

Explicit when-to-use ('Use only when your person asks you to tell, ask or remind a friend something') plus the wording constraint, and it names concrete alternatives for the out-of-scope case ('see my_friends; for someone new, use invite_friend or add_friend first').

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