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

The annotations already establish this as a safe, idempotent, closed-world read, so the bar is lower; the description still adds real context beyond them by quantifying output size (~1.5 KB compact versus ~10× larger for full), capping snapshots at 7 versus 90, and disclosing an Indie plan entitlement 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 with the scope first, then the payload shape, then the mode toggle; every clause carries information. Minor clutter comes from the terse '(trial counts)' parenthetical, which is unclear without context.

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 tool with full schema coverage, rich annotations, and no output schema, the description covers scope, payload contents, both output modes with size tradeoffs, snapshot limits, and the plan prerequisite. Nothing an agent needs in order to invoke it correctly is missing.

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 schema already explains app_id (a Sonar UUID, not a store id) and both fields modes in detail. The description restates the same compact/full distinction without adding syntax, defaults, or error semantics beyond the schema, so the baseline 3 applies.

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 ('Get details for one tracked app'), and defines the payload as store metadata plus daily snapshots of rating, review count, version and installs. It is not differentiated from related read tools such as sonar_app_overview or sonar_app_lookup, so an agent cannot be fully certain which to pick from the description alone.

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?

Gives a useful default-and-override pattern ('Compact by default ... pass fields: "full"'), which implies when the lighter versus heavier mode is appropriate. It does not state when to prefer this tool over sibling read tools like sonar_app_overview or sonar_app_lookup, and the Indie-plan note is presented as a constraint rather than a selection criterion.

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