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

Annotations already declare destructiveHint=true and idempotentHint=false, so the description's added value is the ownership semantic: the seat gains edit and play rights permanently. It still omits what happens to a prior owner's access and whether the operation can be undone by reassigning.

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 plus a return note, front-loaded with the action and constraint, with no filler or repetition of the title.

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 three-required-parameter tool with full schema coverage and annotation-declared destructiveness, this covers the action, the authorization rule, and the return value. The only real gap is the effect on any existing assignment.

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?

With schema description coverage at 100%, the schema already documents all three parameters including slug-vs-id flexibility for campaign. The description adds no additional meaning about how campaign, character, and memberId interact or what happens on a mismatch.

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?

Names a specific verb and resource ('give a character made here to a player's seat') and clarifies the consequence ('from then on it is theirs to edit and play'). The phrase 'made here' implicitly distinguishes it from sibling add_character_from_beyond, but no sibling is named explicitly.

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 'GM only' clause states a prerequisite, and the ownership-transfer framing implies when this applies. However, it never says when to prefer this over add_character_from_beyond, add_companion, or play_character, nor whether a character must already be seated elsewhere first.

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