Mark Inbox Entry Read

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

The annotations already declare mutation and openness, but the description adds substantial context: the side effect of marking read without claiming the reward, required authentication flow, session-token behavior, rate limits, API-key requirement, error result shape, and detailed HTTP/error semantics. It 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 front-loaded and clearly segmented into purpose, use cases, requirements, side effects, returns, and errors. It is dense but mostly earns its length because the auth and error details are operationally useful, though the error catalog is long and the attachment-amount exclusion is somewhat oddly scoped.

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 explain returns and errors; it does both by stating that the tool returns an updated complete inbox snapshot and by cataloging authentication, conflict, reward, balance, inventory, and rate-limit failures. Given the complexity, it is complete enough for 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 coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema: sessionToken must be the accessToken from horizon_signin_email or horizon_signin_anonymous, and userId must be the one that signed in. It also reinforces that the same entry ID should be retried after a state conflict.

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 verb and resource: marking an inbox entry read for the authenticated player. It also distinguishes the operation from nearby inbox actions by noting that it works on an entry from horizon_get_inbox and marks it read without claiming its reward.

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?

It gives explicit use criteria and exclusions: use when an explicit player action targets an entry returned by horizon_get_inbox, and not for changing the recipient or inventing attachment amounts. However, it does not directly name horizon_claim_inbox or horizon_remove_inbox as the alternatives for claiming or removing, though the error notes imply those workflows.

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