Metafields Get

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

Annotations already declare readOnly=true, idempotent=true, destructive=false, so the safety profile is covered; the description adds real value on top by disclosing the required OAuth scopes and the per-owner_resource scope mapping (products/content/orders/customers) plus the pinned API version 2025-03. It stops short of describing auth failure modes or payload size behavior beyond the fields parameter.

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?

Four short lines, zero filler, and the core action is front-loaded ahead of the endpoint, scope, and version metadata. Every line (purpose, endpoint, scope, version) earns its place.

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?

With no output schema, the description should signal what a metafield record contains (namespace/key/value/owner_resource) and whether a missing ID errors or returns null; neither is covered. Prerequisites and version pinning are well covered, so it is adequate but leaves the return-value gap unaddressed.

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% with all three parameters (id, fields, response_format) documented inline, including an enum default, so the schema carries the burden. The description adds nothing about how id is formed (string vs number, owner-scoped) or what fields accepts beyond what the schema already says; 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 one metafield") and backs it with the exact HTTP endpoint GET /metafields/{id}, so the single-record scope is unambiguous. It never names the obvious alternative (tiendanube_metafields_list_by_resource), so the differentiation is implied by name rather than stated.

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?

There is no when-to-use / when-not-to-use guidance and no mention of the sibling list tool for enumerating metafields or of metafields_create/update for mutations. The scope line conveys a prerequisite (read_*/write_* matching owner_resource) rather than selection guidance, which partly helps but is not usage routing.

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