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

Beyond annotations, it discloses PUT semantics, partial-update merge behavior, stripping of legs, the strict dependency on baseUpdatedAt, and the OUT_OF_SYNC error with 'nothing is written'. This gives an agent an accurate model of the write behavior and failure mode.

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 information-dense with no filler: identity, permission, merge semantics, exclusions, alternatives, and concurrency requirement each appear once and in logical order. Every sentence earns its place.

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 mutating, concurrency-sensitive update tool, the description covers authorization, partial-update behavior, non-writable fields, alternative tools, and the exact pre-read step. The output schema exists, so return details need not be restated.

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?

The input schema exposes no parameters, so the description is the only source of parameter context. It adds the critical baseUpdatedAt requirement and its provenance, plus the legs exclusion, but it does not enumerate which other campaign fields may be supplied.

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?

Opens with 'PUT updates to one campaign by id', a specific verb, resource, and scope. It also carves out what this tool does not do ('legs is NOT writable here'), which separates it from sibling leg-management tools.

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?

States the required caller permission ('contribute' permission, DM or assigned co-DM), tells the agent to read a fresh updatedAt via play_get_campaign before calling, and explicitly routes leg operations to play_add_campaign_leg, play_set_campaign_leg_active, and the rule/item/spell/character tools. This is explicit when-and-when-not guidance.

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