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

Annotations declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, so the basic safety profile is already covered. The description adds the non-obvious behavioral trait: this mutation is gated behind a two-step preview/confirm-token handshake, meaning the first invocation has no side effect. It does not disclose side effects of the final commit (notifications, follower counts), so it is not fully exhaustive.

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?

Two sentences, no filler, front-loaded with the action and identifier source, then the two-step protocol. Every clause carries operational information an agent needs.

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 3-parameter, no-output-schema mutation tool with annotations present, the description covers the action, the identifier source, and the entire confirmation workflow. Remaining gaps are minor, such as behavior on token mismatch/expiry or what the committed call returns, none of which block correct invocation.

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%, and the confirm_token definition already states 'Omit on the first call to get a preview... call again with identical arguments plus this token' — the description restates that same contract rather than adding new parameter detail. The one marginal addition is that userId/username come from search_users, which sits at the expected baseline for a fully-documented schema.

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?

Specific verb ('Follow') plus resource ('someone'), with the accepted identifier forms named (username or userId). It also points to the sibling that supplies those identifiers (search_users), so an agent can distinguish it from unfollow_user or block_user without opening a 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 gives explicit call sequencing: first call previews only and returns confirm_token, second call repeats with identical arguments plus the token after user agreement. It also tells the agent where identifiers come from (search_users). It stops short of naming explicit exclusions (e.g., use unfollow_user to reverse), so it is clear context rather than full when/when-not guidance.

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