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

Annotations already cover the safety profile (write, non-idempotent, non-destructive, open-world), so the description's job is to add beyond that. It does: plan gating, auth/scope requirements, and the cardinality rule that a product holds at most one iOS + one Android app. It stops short of saying what happens if the slot is already occupied or if the store_id doesn't resolve.

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 dense sentences, front-loaded with the 'WRITE tool' signal and the core action before the example, alternative, and prerequisites. Every clause carries information; none is redundant with the schema.

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 four-parameter write tool with no output schema, the description covers action, alternative, prerequisites, and the cardinality constraint. Only the failure/edge-case behavior (slot already filled, unresolvable store_id) is absent, which is a minor gap rather than a blocker.

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%, including the enum values, country code format, and the iOS-track-ID vs Android-package-name distinction for store_id, so the schema does the heavy lifting. The description adds no parameter syntax or format detail beyond that, making the baseline 3 correct.

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 ('links the second-store version of an existing Sonar product') and immediately illustrates it with a concrete iOS/Android example. It also distinguishes itself from sonar_create_product by scope, so an agent can route correctly without opening either schema.

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 when-to-use ('the product already tracks the iOS app and you want to add the Android version'), explicit when-not ('to start tracking a brand-new app, use sonar_create_product instead'), and names prerequisites (Indie plan, authorized account or write-scope API key). Nothing 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.