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

Annotations already carry readOnly/idempotent/non-destructive, so the safety profile needs no restating. The description adds genuinely new behavioral context: the return shape (plain-language headline, body, why-it-matters, caveats, plus the paper), newest-first ordering, and the editorial scope limit that only story-selected papers appear. It stops short of describing pagination/volume behavior, which the schema handles instead.

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 tight sentences: use case, what gets returned, filters plus alternative. The opening use-case list ('what happened this week... a short list for a journal club') is slightly wordy but earns its place by anchoring intent. Front-loading is good, though it starts with intent rather than the action.

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 7-param, filter-only list tool with no output schema, the description supplies everything an agent needs: what a story contains, ordering, the story-selected scope, usable filters, and the routing alternative. Nothing about invoking it correctly is left unstated.

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 schema already explains matching semantics ('A paper matches when it involves any of them', cursor reuse guidance, date formats). The description only restates the filter dimensions ('Narrow by category, body system, study type or publication date') without adding interpretation, so the 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?

States a specific verb and resource ('Lists the stories AgingResearch.News wrote about new papers, newest first') and immediately scopes it ('each checked against its paper'). It explicitly distinguishes itself from the sibling search_papers by contrast: 'Only the papers chosen for a story; for every paper on a question use search_papers.'

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?

Opens with a concrete when-to-use trigger ('when the user wants a readable round-up of recent findings: what happened this week... or a short list for a journal club'), then names the excluded case and the alternative tool by name. The routing decision between list_stories and search_papers is fully specified.

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