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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the mutation/idempotency profile is largely covered. The sentence 'Removing a tag the contact doesn't have succeeds' usefully confirms that a no-op does not raise an error, but it mostly restates the idempotentHint rather than adding new behavioral context such as auth requirements or response shape.

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 short lines with no filler, and the core action is front-loaded ahead of the edge-case note. The second sentence is slightly awkwardly phrased but earns its place by clarifying the no-op outcome.

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 mutation with no output schema and good annotation coverage, the description is minimally adequate. It omits any note on the contactId identifier format (a Cuid2), permissions, or what the tool returns, leaving a modest gap for an agent to fill.

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 only 50%: tagRef is well documented in the schema (ID-or-name, case/accent-insensitive, ID wins), but contactId has no description at all and the description text adds nothing about either parameter. The description does not compensate for the undocumented contactId, which is a required 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 states a specific verb and resource ('Remove tag from contact'), which is unambiguous and pairs naturally against the sibling contacts_addTag. It does not explicitly name the sibling or scope the operation beyond the name, but an agent can identify the tool's job immediately.

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?

There is no when-to-use guidance, no prerequisite or permission note, and no mention of alternatives such as contacts_update. The only additional sentence addresses behavior on a missing tag, not usage selection, so the agent must infer context from the name alone.

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