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

Goes well beyond the readOnly/openWorld annotations: it discloses the public no-key upstream, the 20-id batch ceiling, the absence of abstracts, the exact price ($0.002 USDC via x402 on Base/Solana/Arc), and the important billing nuance that failed calls are not charged. That paid-tool cost model is the kind of detail an agent cannot infer from structured fields.

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 what, from where, and which fields, then limits, then alternatives, then price — a sensible order with no filler. The pricing sentence is necessarily dense (currency, protocol, chains) but every clause is load-bearing for a paid call.

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?

An output schema documents return values and annotations cover the safety profile, so the description only needs limits, source, and cost — all present. An agent has enough to decide to call it, batch correctly, and understand the charge.

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% and the single parameter already documents the comma-separated format and the 1–20 range. The description only restates the cap ("up to 20 ids") without adding format, validation, or behavior detail, so baseline 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?

Names the specific resource (PubMed article metadata), the identifier type (PMID), the upstream source (NCBI E-utilities esummary), and enumerates the returned fields (title, journal, publication date, authors, DOI). It also distinguishes itself from the named DataCite sibling, so an agent can pick it without opening the 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 explicitly routes one alternative case ("search_datacite_metadata when you need DataCite DOI search") and states the negative constraint (summary fields only, no abstracts). However, the nearest competitors on this server — search_europe_pmc_articles, search_crossref, search_unpaywall — are never mentioned, so the routing is only partial.

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