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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered; the description adds genuinely new behavior (chunked retrieval, the next_offset continuation protocol, licence and sha256 in the response, and the open-access-links fallback in rows). That is meaningful context beyond the annotations, though it does not mention rate limits or what happens on a failed/unknown ID.

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?

Three sentences, front-loaded with the core action and pagination contract, followed by return-value and fallback notes. Every clause carries information an agent needs; nothing is repeated from the schema or annotations.

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 3-parameter read tool with an output schema already present, the description covers the retrieval mechanics, the pagination termination rule, the degraded-mode return shape, and accepted ID formats. An agent can invoke and iterate this tool correctly without further guessing.

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?

With 67% schema coverage (max_chars has no schema description), the description compensates by documenting the 40000 cap and the offset/next_offset pagination loop, including the termination condition. It also enumerates the accepted identifier forms (DOI, OpenAlex ID, PMID, PMCID) beyond the schema's single-line note, and introduces next_offset, which is not an input parameter at all.

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 names a specific verb and resource — reading the full text of an open-access paper from PubMed Central (PMC BioC) — and scopes it to open-access content, which sets it apart from search_literature, get_papers and the citation-network siblings. It stops short of naming an alternative tool for the case where the caller wants metadata rather than full text, so it is clear but not fully sibling-differentiated.

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 concrete calling context: pass offset=0 to start, continue from next_offset until null, and it flags the fallback behavior when PMC has no text. There is no explicit statement of when NOT to use this tool or which sibling to prefer for metadata-only lookups, which keeps it below a 5.

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