tag_thread

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

With no annotations, the description carries the full behavioral disclosure burden. It explicitly states 'Tags are additive — existing tags are preserved', which is a key non-obvious behavior. It also clarifies the comma-separated format. It does not cover edge cases like duplicate handling or permission requirements, but the core behavior is well disclosed.

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 tightly structured: a one-sentence purpose, a usage note, and an Args block. Every sentence contributes vital information without redundancy or fluff.

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 tool, the description covers purpose, behavior, and parameter format. The output schema exists, so return values need not be described. Minor gaps like idempotency or error handling are not critical for basic usage, so this is nearly complete for the tool's complexity.

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%, so the description must compensate. It does so by explaining both parameters: thread_id is identified simply, while tags gets a clear format and example ('Comma-separated tags to add (e.g. "urgent,vip,sales-lead")'), adding significant meaning beyond the bare 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?

The description clearly states 'Add tags/labels to a thread' with a specific verb and resource. It differentiates from sibling tools like untag_thread by explicitly noting the additive behavior, making its purpose unambiguous.

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 description provides examples of tag usage ('vip', 'bug-report', etc.) and shows a concrete argument format, which implies when to use this tool. However, it does not explicitly contrast with alternatives like untag_thread or state when not to use it, leaving usage guidance somewhat implied rather than explicit.

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