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

Annotations already declare the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is behavioral context beyond that. The description adds genuine value: it enumerates returned fields, discloses that abstracts are HTML-stripped, notes the file listing is capped at 5 files with sizes and EOS URIs, and states typical licenses (CC0/CC-BY). This gives the agent an accurate expectation of output shape and quirks beyond what annotations convey.

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 core action is front-loaded in the first sentence, followed by a dense but purposeful enumeration of return fields, then usage guidance. The field list is long but each item is concrete and informative for an agent deciding whether this tool meets the user's need; nothing is redundant filler.

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-parameter read tool with a rich output schema and safety annotations, the description is complete: it states the operation, the input acquisition path, both ID formats, the fields returned, and licensing. An agent can invoke this tool correctly with no lurking unknowns, and the output schema covers return details.

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%, so the input schema already fully documents the id parameter including examples and the numeric-vs-string-anchor distinction. The description repeats this information ('IDs can be numeric... or string anchors for glossary terms'), adding marginal reinforcement but no new semantic content beyond 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?

The description opens with a specific verb-resource pair: 'Fetch full metadata for a specific CERN Open Data record by its ID.' This unambiguously distinguishes it from siblings like cernopendata.records.search (discovery) and cernopendata.datasets.browse (dataset listing). The single-record-by-ID scope is stated clearly and the title reinforces it.

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?

Explicitly directs the agent to 'Use cernopendata.records.search or cernopendata.datasets.browse to discover record IDs,' which tells the agent how to obtain the required input. It also clarifies the two valid ID forms (numeric and string anchors for glossary terms), linking conceptually to cernopendata.glossary.lookup. It lacks an explicit exclusion statement ('do not use when...'), but the guidance is clear and actionable.

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