invariance_capture_update

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

Annotations already mark this as a write operation (readOnlyHint=false, destructiveHint=false). The description adds context that captures are standalone evidence and don't require an execution upfront, which is useful. However, it doesn't disclose side effects beyond what's stated, such as whether metadata merging is destructive or if tags are replaced (though that's in the schema). No contradiction with annotations.

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 tightly written sentences. The first sentence front-loads the core operations, and the second clarifies the capture's standalone nature and points to the link tool. No wasted words; every sentence 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?

Given there is no output schema and the input schema fully documents parameters, the description is adequate for an agent to correctly invoke the tool. It explains the standalone nature of captures and how linking works, which is important context. It doesn't cover error cases or prerequisites, but those are not essential for a straightforward mutation tool with a single required parameter.

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%, so all five parameters are already documented. The description's mention of 'merge metadata' aligns with the schema's 'shallow-merged', and 'reassign run_id' matches the schema, but it adds little beyond what the schema provides. It doesn't mention tags at all, but since schema covers them, the baseline of 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?

The description uses the specific verb 'Update' with the resource 'capture' and enumerates the exact operations (change status, reassign run_id, merge metadata). It clearly distinguishes from invariance_capture_link by noting linking is done separately, so an agent can tell this tool apart from its sibling.

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?

It explicitly states when to use the link tool instead ('link a capture to a run later with invariance_capture_link'), providing a clear alternative. While it doesn't list every when-not scenario, the main disambiguation is covered, and the intended use (modifying an existing capture) is implicit but obvious.

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