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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description does not need to repeat that it's a safe read. It adds valuable behavioral context: the follow relationship data is Instagram-only and only available for contacts who have messaged, plus the note that follower lists are not available on any channel. This goes beyond the structured hints and helps the agent set expectations.

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 two sentences and avoids padding. The first sentence front-loads the core purpose ('One contact:') and immediately lists the output fields, making it easy to scan. The second sentence clarifies a key limitation. It is concise and efficient, though a more explicit action verb like 'Retrieves a single contact by ID' would strengthen it further.

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?

There is no output schema, so the description must convey return semantics, and it does by itemizing the fields. It also highlights the Instagram-only caveat and the lack of follower lists, which is important context. Given the tool's simplicity (read-only, one required parameter) and the annotations covering safety, the description is largely complete. It could mention what happens if the contact does not exist or the meaning of 'refresh', but those are minor.

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?

The input schema covers refresh and workspaceId with descriptions, so across 3 parameters, coverage is 67% (above 50%), giving a baseline of 3. The description adds no parameter-specific meaning; it does not explain what 'refresh' does or when workspaceId is needed beyond what the schema already says. Thus the description neither compensates for gaps nor adds value, so a baseline 3 is appropriate.

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 the tool retrieves a single contact and enumerates the exact fields returned (name, username, follow relationships, follower count, tags, opt-out, messaging window close). It also distinguishes itself from listing tools by explicitly noting that follower lists do not exist on any channel, making it clear this is the only way to get such data. This is a specific verb+resource with clear scope.

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 provides no guidance on when to use this tool versus alternatives like list_conversations or list_mentions. The only hint is 'Follower lists do not exist on any channel; this is the closest thing,' which implies it's the way to get follow status but does not explicitly say 'use this when you need a single contact's profile' or 'don't use this for bulk contact listing.' No exclusions or alternatives are named.

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