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

Annotations already declare readOnlyHint=false, destructiveHint=true, and idempotentHint=false, so the description is not carrying the safety burden alone. It still adds real value by spelling out the side effect ('records the caller as claimant') and enumerating the return payload, which compensates for the absence of an output schema. It does not explain what the destructiveHint refers to or what happens if the investigation is already claimed, leaving a gap.

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, no filler. The claim semantics and the read-only alternative are front-loaded ahead of the return-value enumeration, which is the least critical part.

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 one-parameter tool with no output schema, the description covers invocation, the mutation's meaning, the read-only alternative, and the return fields. The remaining gap is conflict/error behavior (already-claimed investigations, reversibility of the claim), which an agent would need before acting in ambiguous cases.

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% and the schema already states 'Investigation UUID or public slug', so a 3 would be defensible. The description earns the extra point by giving a concrete slug format example ('happy-otter-42'), which materially helps an agent recognize and pass a valid value.

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?

Specific verb + resource + effect: 'Claim a Fixter investigation for the calling user and fetch its full transcript.' It also explicitly names the sibling it is not (get_investigation_brief), so an agent can route between the two without opening either schema.

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 an explicit when-to-use condition ('only call it when the user intends to work on the investigation') and an explicit alternative for the read-only case (get_investigation_brief). Nothing about tool selection is left to inference.

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