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

Annotations already declare readOnlyHint=false, openWorldHint=true and idempotentHint=false, but the description supplies the reason — each call 'logs to the audit trail' — which explains the non-read-only, non-idempotent profile. It also discloses the 30-day recency window and the absence of free-text search, meaningful traits beyond the annotations. Return format and rate limits remain unstated.

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 critical constraint is front-loaded in the first two sentences, followed by a compact Args block. Given 0% schema coverage the parameter list earns its place, though the 'Args:' section is somewhat more verbose than strictly necessary.

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 4-parameter tool with no output schema and partial annotations, the description covers the calling contract, the audit-logging side effect, and the API's structural limitation. What an agent needs to call it correctly is present; pagination and result-count behavior are the only unaddressed items.

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 0%, so the description carries the full burden and does so: it documents all four parameters with concrete examples ('neuroscience', 'aletheia:advocate'), allowed values for server and category, and the max_results default. Only minor gaps remain, such as the upper bound on max_results.

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 states a specific verb and resource ('List bioRxiv/medRxiv preprints by category') and immediately resolves the misleading 'search_' prefix by declaring 'No free-text search exists on this API — only category listing (last 30 days).' That contrast lets an agent distinguish this capability from true search siblings like search_pubmed and search_europepmc without opening a schema.

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 clear context for when the tool applies: category listing only, last 30 days, no free-text search. It does not, however, explicitly route between this and the other search_* siblings, so the agent must infer that a keyword query belongs elsewhere.

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