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

The annotations already declare non-readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuinely new behavior: the note is private to the user ('only they see it') and an empty note clears the existing note — a deletion semantic not captured by any annotation.

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 short sentences, front-loaded with the core purpose, with the privacy and clearing semantics placed after the example. Every sentence carries information, though the illustrative quote is slightly dense relative to the rest.

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?

With an output schema present, return values need not be explained, and the idempotent hint plus the 'empty note clears it' sentence conveys overwrite semantics. Missing is any indication of how the target contact is selected (handle vs conversationId), which matters for a 3-parameter upsert tool.

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 only 33%, so the description carries much of the burden. It gives a content example for 'note' and implies brevity, but says nothing about 'handle' vs 'conversationId' as alternate targets or the 500/40 character limits, leaving a key identification parameter undocumented in both places.

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 operation on a specific resource — a personal note attached to someone the person has talked to professionally — and the example ('recruiter at Acme, role closes Nov 1') pins down scope and content. It distinguishes itself from the surrounding pro_* siblings by the 'professional contact' framing, though it never names an alternative tool explicitly.

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?

There is no explicit when-to-use or when-not-to-use guidance and no named alternatives among the many sibling tools (pro_message, pro_profile, pro_search). The only implied constraint is that the handle must already be a professional contact, which comes from the schema, not the description.

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