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

Annotations already set destructiveHint=true, and the description reinforces this with 'MUTATES LIVE STORE DATA' and 'Partially update'. It adds context about live store data and the partial-update behavior, going beyond the annotation. No contradiction.

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 short, impactful sentences. The warning is front-loaded, then the usage pattern, then the API endpoint for reference. No filler or redundant text.

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 2-parameter mutation tool with destructiveHint, the description fully covers the essentials: what it does (partial update), required inputs (id, fields), and the underlying API. Given low complexity and full parameter schema, no significant gaps remain.

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% and both parameters are well-described in the schema (id required; fields with example). The description repeats this guidance but doesn't add new semantic detail beyond what the schema already provides. Baseline 3 is appropriate.

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 states a specific verb ('partially update') and resource ('existing product by id'), and includes the API method PUT /products/{id}. This clearly distinguishes it from sibling tools like swell_create_product (create new) and swell_get_product (read).

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 explicit usage guidance: 'Provide the id plus a fields object.' It implies the product must exist and clarifies partial update semantics, though it doesn't explicitly state when to prefer this over create or when not to use it. Sibling context makes the use case clear.

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