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

With no annotations, the description carries the behavioral burden and does well: it discloses that reading one device costs the same as a list read, that re-reading is free, and that sourceUrl points to the authority's own record for verification. It does not mention error behavior or rate limits, but for a simple getter this is reasonably transparent.

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 front-loaded with the core purpose and is information-dense rather than padded. The enumeration of market-specific fields is long but earns its place by clarifying exactly what richer data is available. It could be trimmed, but every sentence contributes.

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?

Given only one parameter, no output schema, and no annotations, the description covers the return payload meaningfully—list fields, registryFields, and sourceUrl—and adds cost semantics. It does not explain what happens on invalid IDs, but the parameter provenance and high schema coverage make this adequate for a single-record getter.

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 parameter registration_id is already documented in the schema with its provenance from get_registrations, find_similar_devices, or get_recent_registrations. The description adds little parameter-level meaning beyond referring to 'that row,' so the baseline of 3 applies.

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 title and opening 'One registration, complete' state a specific verb and resource, and the description explicitly contrasts with get_registrations by saying it returns everything from the list row plus registry-specific fields. This clearly distinguishes it from sibling tools like get_registration_timeline and get_recent_registrations.

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 description makes it clear this is the exhaustive single-record counterpart to list operations, mentioning fields that 'fit a list row' versus full detail. It implies when to use it, though it does not explicitly name alternative tools or state when not to use it. The context is strong but exclusions are left implicit.

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