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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered; the description still earns credit by adding that the data is read live from App Store Connect (not cached) and by enumerating the possible App Review states an agent will encounter. It also discloses a domain rule that affects interpretation: an offer requires a minimum paid duration, so free-trial users are not eligible. Missing are any notes on latency, error modes, or scale of the response.

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 verb and resource are front-loaded, but the body collapses into two very long, parenthesis-heavy sentences that bundle return shape, domain rules, and parameter behavior together with no sentence breaks. Every clause is informative, yet the density makes it hard to scan for the one line that matters most: what retentionOfferId does.

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 two-parameter read with no output schema, the description does the heavy lifting: it describes the returned structure in detail and explains the mode-switching parameter. What it lacks is an explicit statement about appId and any confirmation of what the response looks like when retentionOfferId is supplied (single offer versus full listing).

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 0%, so the description must carry the load, and it does for the non-obvious parameter: retentionOfferId changes the operation into a per-territory price read for that offer, which an agent could not infer from the schema alone. appId is only indirectly conveyed ("the app's ... messages") with no format or requiredness note, which keeps this short of a 5.

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 ("Read, live from App Store Connect, the app's Apple retention messages") and immediately parenthesizes what that resource means to a subscriber. No sibling tool in the list touches retention messages or offers, so the resource is unambiguous, and the enumeration of nested content (versions, review state, locale copy, images, attached subscriptions, offers) makes the scope unmistakable.

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 implies the usage context by explaining what a retention message is ("what a subscriber sees when they start to cancel") and by noting that supplying retentionOfferId switches to reading that offer's per-territory price. But it never states when an agent should call this versus another tool, nor any prerequisites or exclusions, so routing 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.