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

Annotations already declare read-only, idempotent, closed-world behavior, so the bar is lower. The description still adds real value by disclosing what the records contain (exact DOI/NCT identities, report roles, source URLs, check dates, limitations) and, importantly, that coverage is incomplete. That incompleteness warning materially changes how an agent should reason about the results.

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 sentences, each carrying distinct information: scope, invocation modes, and payload plus caveat. The scope sentence is front-loaded and nothing is padded, though the field list is slightly dense for a single clause.

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 single-optional-parameter read tool with an output schema already present, the description covers purpose, both invocation modes, and the key interpretive limitation. Little is missing; only the relationship to the sibling relationship/citation tools is left unstated.

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?

The schema already documents the single optional 'id' parameter at 100% coverage, including the warning that it is a numeric string rather than a DOI or URL. The description reinforces this by framing the parameter as an optional 'visible record ID' whose omission switches to catalogue mode, adding behavioral meaning beyond type information.

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 uses a specific verb and resource: 'Read selected source-checked links between registrations, protocols, preprints, primary reports and follow-up analyses.' That is far more than a restatement of the name. It does not, however, contrast itself with the closely named sibling get_citation_relationships, so an agent must infer the distinction.

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 operating modes: supply a record ID to inspect that record's families, or omit the ID to get the small reviewed catalogue. The closing caveat ('never assume unlinked records are independent studies') tells the agent how to interpret negative results. It stops short of naming an alternative tool or stating when not to use this one.

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