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

Annotations already establish write behavior, idempotency, and non-destructiveness. The description adds important constraints beyond those: 'Coordinates are WGS84 only and are never silently geocoded,' source provenance is mandatory, and new Places require a canonical key plus durable identifier. This is useful behavioral context without contradicting the annotations.

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?

Four dense sentences with no filler. The main action is front-loaded, followed by prerequisites and constraints, and every sentence adds information the agent needs.

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 complex 11-parameter mutation with no output schema, the description covers prerequisites and key constraints but omits important operational details such as how value/coordinates should be structured, idempotency semantics, and what a successful or failed assertion returns. It is adequate but has clear gaps.

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 clarifies source provenance, new Place canonical_key/identifiers, and WGS84 coordinates, but leaves many parameters unexplained, including value, qualifiers, visibility, valid_from/valid_to, observed_at, and idempotency_key.

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 the verb and resource: 'Add a governed location assertion for an existing eligible subject.' This distinguishes it from reading or resolving assertions, though it does not explicitly name a sibling alternative.

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?

It gives explicit procedural guidance: 'Resolve the subject and any existing Place first' and specifies requirements for new Places. It does not explicitly state when not to use this tool or name alternatives, so it stops short of a 5.

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