register_candidate

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

With no annotations, the description carries the full burden and handles it well: it discloses the lineage invariant ("every candidate keeps its ancestry", no latest-wins), the referential constraint (parent_id must name an existing candidate), and digest enforcement (must resolve to an ingested blob or be 'none'). It is silent on permissions, idempotency, and duplicate handling, which are relevant for a write operation.

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?

Purpose is front-loaded in the first sentence, and the enforcement paragraph is the most actionable content. Some sentences are conceptual prose ("The thing doing the research becomes a durable object", "a hash of nothing is a claim with no referent") that add flavor rather than call guidance, slightly inflating length.

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?

An output schema exists, so return values need not be explained, and the description covers the lineage model and validation rules an agent needs. It remains incomplete on operational behavior for a mutation — auth requirements, idempotency, and error semantics on invalid parent or unresolved digest are not stated.

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 100%, so parent_id ("omit for genesis"), capability_profile ("object or JSON-encoded"), and the digest fields are already documented. The description mostly restates these; its only marginal addition is the phrase explaining that 'none' means no referent, which is a modest value-add over the schema.

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?

States a specific verb ("Register") and resource ("a researcher version") and frames the scope with the RSI Phase 0 label plus the lineage concept. It is legible apart from read-only siblings like get_candidate_lineage or list_candidates because it explicitly denotes a creation/registration action with ancestry.

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 a clear conditional for the key decision — "omit for a genesis candidate" vs supplying parent_id — which tells the agent when the parent link applies. It does not name alternative tools or state exclusions (e.g., when to read lineage instead of register), so it stops short of full when/when-not guidance.

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