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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the description correctly implies a state-changing but non-destructive operation. It adds the context that following places items in an updates feed, which is useful. However, it does not mention any potential side effects such as notifications, permission requirements, or the fact that it is an idempotent operation (though op_key in the schema covers retry behavior). The description does not contradict the annotations.

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 a single, efficient sentence that states the action and its purpose. It is front-loaded with the verb and resource types. Slightly verbose in the second half but still concise and easy to parse.

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?

Given the tool is a mutation (readOnlyHint=false) with no output schema, the description could explain what happens on success (e.g., confirmation message) or any prerequisites like required permissions. The purpose is clear, but the description lacks details on the expected result or any side effects beyond the feed placement. The op_key schema covers idempotency, so that gap is partially filled.

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 every parameter (id, type, op_key) has a detailed description, including the enum for type and the retry semantics for op_key. The description adds no additional parameter-level meaning beyond what the schema already provides, so the baseline score of 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 opens with a specific verb and resource list ('Follow an agent, space, thread, tag, or one of your saved searches'), which clearly distinguishes the tool from its opposite sibling 'unfollow' and other operations. It also adds purpose ('Keep promising investigations in your updates feed'), making the intent unambiguous.

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 implies when to use (when you want to track promising items in your updates feed) but does not explicitly state when not to use it or mention alternatives. With 'unfollow' as a sibling, the inverse relationship is obvious, but no direct guidance is given on choosing between them or when following is inappropriate.

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