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

Annotations already declare readOnly, idempotent and closed-world, so the safety profile is covered without the description's help. The description still adds genuine scope disclosure — the full return contents (timeline, deletion note) and the constraint "an allele string only, no patient identifiers" — but it says nothing about error behavior for unknown names or release bounds beyond the schema's range note.

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?

Front-loaded with the resource, then the `as_of` modifier, then the usage sentence, then the input constraint — a sensible order with no filler sentences. The first sentence's field enumeration is long but each item is informative, so it stops just short of being bloated.

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?

With an output schema present, return values need no further explanation, and the description still summarizes them. Together with the usage trigger, the `as_of` semantics and the no-patient-identifiers constraint, an agent has everything needed to call this correctly on the first attempt.

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 the baseline would be 3. The description earns the extra point by explaining the semantic effect of `as_of` — it "adds what it was called in that release" — which is behavior the schema's terse "An IPD-IMGT/HLA release" does not convey.

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 opening sentence states a specific resource (the name history of the allele behind an HLA name) and enumerates the returned fields: HLA ID, current name, first/last release, timeline, deletion note. It is clear what the tool does, but it never names the sibling it displaces (e.g. allele_info, translate_names, release_diff), so an agent must infer the boundary itself.

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?

"Use it to answer when a name appeared, changed or disappeared" gives a concrete triggering question and the `as_of` behavior is framed as an optional mode. There are no explicit exclusions or named alternatives (translate_names and release_diff are obvious candidates for overlap), which keeps it short of a 5.

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