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

With no annotations, the description carries the full burden and does well: it discloses the endpoint, that the indexer verifies/derives everything from chain data, the outcome codes (201 new / 200 duplicate / 422 invalid) which reveal idempotent duplicate handling, and that the response is returned verbatim. It doesn't cover auth/rate-limit or retry guidance, keeping it short of a 5.

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 dense sentences, front-loaded with the action and endpoint, followed by verification semantics and return behavior. No filler; every clause conveys information an 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 one-param, no-annotation, no-output-schema tool, the description covers the action, the endpoint, verification semantics, the status-code outcomes, and the verbatim return. That is nearly everything an agent needs; only auth/permission expectations and retry guidance on 422 are absent.

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 single txid param is already fully documented in the schema (64-hex transaction id of an already-broadcast tx). The description adds only the body placement ({txid}), so the schema does the heavy lifting – baseline 3.

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 a precisely scoped resource (a self-broadcast Locus transaction against the reference indexer), and even names the underlying endpoint POST /v2/pins {txid}. This is clearly distinguishable from the pin-read siblings (get_pin, list_pins) and the build/payload siblings.

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 word 'self-broadcast' and 'already-broadcast tx' imply a precondition (the tx must exist on chain first), but the description never states when to reach for this versus other tools, nor any explicit prerequisite or exclusion. Usage is implied rather than spelled out.

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