grocy_barcode_lookup

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

Annotations mark the tool readOnlyHint=false and openWorldHint=true, but they don't explain the dual-mode nature. The description adds real value by clarifying that the default is a read and a write only happens when add=true, gated by confirm — a nuance the blanket readOnlyHint=false does not convey. It still omits failure behavior for unknown barcodes and rate/network concerns of the external call.

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 sentences, front-loaded with purpose followed by the write caveat. The raw REST path is somewhat low-value for an agent consuming an MCP tool, but it is compact and nothing is padded.

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 never says what an external lookup actually returns (product identification fields? not-found signal?), which is the core question for a lookup tool. The write path is reasonably documented, but the read result is left opaque.

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 67%, and both 'add' and 'confirm' already have thorough schema descriptions (including that confirm must be the boolean true and false/string values are rejected). The description only restates that add creates a product and needs confirm, adding no syntax or semantics beyond the schema.

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 ('External barcode lookup') and includes the underlying endpoint, so the agent knows it queries a barcode against an external source. The qualifier 'external' implicitly separates it from grocy_stock_product_by_barcode, but the sibling is never named, so the distinction must be inferred.

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?

'add=true also creates the product and needs confirm' implies two modes (lookup-only vs lookup-and-create), which gives some usage context. However there is no explicit guidance on choosing this over grocy_stock_product_by_barcode for local lookups, and no statement of prerequisites for the external call.

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