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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the bar is lower. The description adds genuine value by enumerating the record contents (completion state, test flag, creation time) and the backing GraphQL query, but says nothing about error behavior on a missing/invalid eid or any access constraints.

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?

One tightly packed sentence: verb and scope first, the parenthetical definition immediately after the resource, then the return fields and the query name. No filler, nothing redundant, fully front-loaded.

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 usefully summarizes the returned fields, and it correctly frames the entity relative to the workflow. It is slightly incomplete in not covering failure modes or whether the field list is exhaustive, but for a single-parameter read this 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 description coverage is 100% and there is a single required parameter, so the schema fully documents eid. The description only adds 'by eid', which is already visible in the schema; it contributes no format, validation, or lookup-semantics detail beyond that. 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 (Fetch) and resource (a weldData record), and crucially defines that resource as 'a single submission to a weld (workflow)', which separates it from the sibling anvil_get_weld (the weld itself). It also names the underlying GraphQL query, so an agent can identify the exact operation.

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 definition of 'weldData = a single submission to a weld' implicitly signals when this tool applies versus anvil_get_weld, but there is no explicit when-to-use statement, no alternative named, and no precondition guidance (e.g., what to do if the eid is unknown or belongs to a different entity type). Usage is inferable but not spelled out.

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