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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety and repeat-call profile is covered. The description adds the domain restriction (only redeem code guides can be followed) and a brief return note, but says nothing about what happens when a non-redeem-code guide is passed, whether an existing follow is replaced, or any auth requirement.

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 front-loaded sentences that begin with the trigger condition, then the eligibility constraint, then identifier sourcing. The semicolon-joined sourcing sentence is dense but every clause carries actionable information and nothing is wasted.

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 2-parameter, non-destructive subscription tool with an output schema and full schema coverage, the description covers the trigger, the guide-type restriction, and where the identifiers come from. Remaining gaps are edge-case error behavior and lifecycle guidance versus unfollow_codes/my_code_follows, which are minor given the tool's simplicity.

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 both property descriptions already state that guide comes from search_guides/my_saved_guides/my_code_follows and that locale is the locale of that search_guides result. The description largely repeats that text ('pass the search result's locale'), adding emphasis but no new semantics such as format or default locale behavior.

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 action and resource: subscribing the user to alerts for new redeem codes on a particular guide, and it clarifies the scope ('Alerts come only for redeem code guides'). It does not explicitly name unfollow_codes or my_code_follows as the contrasting operations, so sibling differentiation is partial rather than complete.

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?

'Use when the user asks to get alerts when new redeem codes come out for a game' is an explicit trigger condition, and the note that alerts exist only for redeem code guides is a real eligibility constraint. What is missing is the negative case: it never says to use unfollow_codes to stop alerts or my_code_follows to inspect existing follows.

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