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

Annotations already declare the mutation profile (destructive, idempotent, openWorld), so the bar is lower; the description still adds real value by explaining that contacts keep the tag under its new name, i.e. associations are preserved rather than deleted. It does not address permissions or duplicate-name behavior, keeping it at 4.

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 with the core action front-loaded and the preview option last; every sentence carries information 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 covers the operation's effect and the preview option adequately, and annotations carry the safety profile. It leaves out what happens when the new name collides with an existing tag, a minor but real gap for a rename tool.

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 100%, so the schema already documents tag_id, name limits, and dry_run; the description only echoes the dry_run preview hint. No additional semantics are added beyond what the structured fields provide, matching the baseline of 3.

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 and resource ('Rename a contact tag') that narrows the generic update_tag name, and immediately distinguishes it from create_tag/delete_tag by clarifying the operation is a rename. It also states the consequence on contacts, so an agent knows exactly what the tool does.

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?

Gives concrete usage guidance by recommending 'Set dry_run: true to preview' before applying changes. It does not name alternatives (e.g., update_contact vs remove_tag_from_contact) or state when-not-to-use, so it stops short of 5.

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