Inspect Legacy Achievement Reward Status

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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, but the description goes well beyond them: it discloses that the read is a POST, that no reward, delivery or grant is created, that MIGRATION_REQUIRED preserves legacy originals and never authorizes a replacement, and it maps the 409/401/403/429/ACHIEVEMENT_NOT_MANUAL failure modes to concrete recovery actions. Rate-limit and auth-source behavior are both covered.

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?

Front-loaded with the core action and then labeled blocks (Use when / Not for / Requires / Side effects / Returns / Errors) that make skimming easy. The errors paragraph is dense and partially redundant with the auth block, so it is slightly longer than it needs to be, but every section carries operational information.

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?

No output schema exists, yet the description supplies the return shape ({achievements,results:[{key,state,inboxEntryId,code}]}) and interprets edge cases (compact achievements have no Inbox ID). Combined with error handling, side effects and auth prerequisites, an agent has everything needed to call and interpret this correctly.

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%, so the baseline is 3. The description adds genuine meaning on top: it explains where sessionToken comes from (the accessToken of a prior sign-in) and ties userId to the signed-in player ('pass the userId that signed in' on a 403), and it reinforces the fixed one-to-eight key bound and the 'never invent a replacement key' rule for retries.

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?

States a specific verb and resource: 'Reads compatibility reward status for up to eight original achievement keys.' It draws a hard boundary against the achievement siblings with 'Not for: delivering or claiming new achievement rewards; new unlocks credit immediately,' which separates it from horizon_unlock_achievement and horizon_get_achievements. It also implicitly corrects the misleading 'deliver' in the tool name.

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?

Explicit 'Use when' (diagnosing an older unsettled reward without changing its original identity) and explicit 'Not for' (delivering or claiming new rewards). Prerequisites are spelled out: sign in via horizon_signin_email or horizon_signin_anonymous and pass its accessToken as sessionToken, plus the HORIZON_API_KEY requirement. Nothing about when to reach for this versus a sibling is left to inference.

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