fetch_articles

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

Annotations already declare readOnlyHint=false and openWorldHint=true, so the external/state-mutating nature is partly covered. The description adds real value by disclosing the free-full-text-first fallback strategy and the loop-until-exhausted behavior, but it doesn't explain why it is non-read-only (that results are stored) or mention rate limits against the open-access sources.

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?

Two compact sentences that lead with the main action and the source strategy, with no padding. The trailing "Rules: guide('fetch')" is slightly cryptic but is a useful pointer rather than waste.

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 exists so return values need not be described, and annotations carry the safety profile. The description supplies the pipeline context (source waterfall, repeated invocation until remaining hits zero) and routes to guide for rules, which is sufficient for an agent to call it correctly; only the run_id dependency chain is left implicit.

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 80%, so the schema already documents uids, run_id, and the retry flags well. The description adds nothing about parameters (it never mentions run_id, max_items, or the retry semantics), so the baseline 3 is appropriate.

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?

States a specific verb and resource ("Fetch full text of included articles") and even explains the source waterfall (PMC, Unpaywall open access, else abstract), so the agent knows exactly what content it returns. It does not, however, distinguish itself from the related read tools (get_article_page, list_articles), so sibling differentiation is missing.

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 a workflow cue ("repeat while remaining > 0") and defers rules to a sibling via "guide('fetch')", which implies usage context. But it never states when this tool should be chosen over get_article_page or list_articles and gives no explicit exclusions or prerequisites beyond the run_id hint.

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