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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered; the description adds the non-obvious temporal behavior that as_of_seq reads data as it stood at an earlier data_seq. It does not discuss result size, truncation, or rate limits, though the presence of an output schema reduces the need to describe return shape.

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?

Four tight sentences, front-loaded with capability then routing then the temporal parameter; every clause carries either a routing or a behavioral fact. Nothing is padded or repeated.

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 two-parameter read tool with full schema coverage, rich annotations and an output schema, nothing material is missing: the agent knows what it returns, which IDs work, when to prefer siblings, and how to time-travel. Return-value detail is correctly delegated to the output schema.

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 both parameters are already documented in the schema, and the description largely restates the same facts (accepted ID forms, as_of_seq for reproducing an earlier answer). It adds no syntax, precedence, or edge-case guidance beyond what structured data already provides, 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?

Opens with a specific verb and resource ('Return one full peptide, publication, finding or trial record') and enumerates the exact ID namespaces it accepts, so the agent knows precisely what entity set this covers. It is also clearly distinguishable from resolve_peptide and the search_* siblings, which are named explicitly.

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?

Gives positive conditions ('known records or fields omitted from compact results') and names three alternatives with the condition that selects each: resolve_peptide for an unclear name, search_publications to find papers, replay_query to repeat a saved search. The when-not-to-use cases are explicit rather than inferred.

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