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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), so the description's burden is lower. It still adds useful behavioral context: results are ordered 'newest first' and gated behind an 'Indie plan (trial counts).' It does not describe pagination behavior or result cardinality beyond the schema's limit cap.

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?

Two sentences, each earning its place: the first defines the returned data and ordering, the second gives the use case. Information is front-loaded with no filler or redundancy.

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?

Covers purpose, change types, ordering, use case, and a plan-gating requirement for a read-only, 3-parameter tool with full schema coverage. The absence of an output schema means the description could have described the return shape, but for a simple list tool the current coverage is close to sufficient.

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 schema already documents app_id, type, and limit with clear descriptions. The description adds no field-level syntax or format details beyond what the schema provides. Baseline 3 applies when the schema does the heavy lifting.

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+resource (change history) and enumerates the exact change types returned (releases, metadata edits, screenshot swaps, price changes, category moves). This clearly distinguishes it from siblings like sonar_app_rankings or sonar_app_overview, which do not track change events.

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?

The description gives a concrete use case: 'correlating rank movements with what the app (or a competitor) changed.' This implies when to reach for this tool, but does not explicitly name a sibling alternative or state when NOT to use it, so it falls short of the 5-level bar.

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