tag_resource

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

With no annotations provided, the description carries the burden of behavioral disclosure. It explicitly indicates an upsert behavior through 'Add or update tags', which is useful. However, it does not mention authorization requirements, tag limits, or consequences of adding a tag with an existing key.

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?

The description is compact and front-loaded with the key usage directive. Every sentence contributes useful information, and the Args section provides parameter semantics without unnecessary detail.

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 simple two-parameter tagging operation, the description covers both the when-to-use context and parameter meaning. The lack of an output schema is acceptable for a mutation tool, and no critical information seems missing for correct invocation.

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 0%, but the Args section compensates by explaining resource_arn as 'Key ARN' and tags as 'List of {Key, Value} dicts'. This adds meaning beyond the raw schema, particularly by clarifying the expected shape and purpose of the tags parameter.

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 clearly states the verb 'Add or update tags' and the resource 'APC key'. This makes it immediately distinguishable from sibling tools like untag_resource and list_tags_for_resource.

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 opening call-to-action 'Call this when adding classification, environment, or ownership metadata to a key' gives clear context for when to use this tool. It does not explicitly mention when not to use it or name alternatives, but the usage scenario is specific enough for an agent to select it appropriately.

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