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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description adds real behavioral context: a 48-hour retention window that causes NOT_FOUND, and a compliance caveat ('Information only — never investment advice'). It does not mention pagination or truncation beyond the 'up to 10' publications cap, which is a minor gap.

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?

Purpose and provenance are front-loaded in the opening clause, followed by the payload contents, the error case, and the disclaimer. Dense but every clause carries information; the payload enumeration is the only part that slightly overlaps the output schema.

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?

With an output schema present, the return shape needn't be explained, yet the description still covers provenance, the failure mode, the retention limit, and the compliance stance for a one-parameter read tool. Nothing an agent needs to call it correctly is missing.

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 coverage is 100% for the single id parameter, and the schema already specifies the UUID pattern and that the value comes from a previous result. The description adds only the provenance detail (which sibling produced the id), 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?

A specific verb+resource (fetch one story by id) with an explicit statement of what the payload contains: headline, summary, instrument coverage, reporting publications, and earlier related stories. It also names the sibling tools that produce the id, so an agent can distinguish it from search_stories and get_instrument_stories at a glance.

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?

The description makes the precondition clear: the id must come from search_stories or get_instrument_stories, and it states the failure condition (NOT_FOUND for an unknown or 48h-stale id). It stops short of an explicit when-to-use versus when-to-use-a-sibling statement, but the id-origin framing effectively routes the agent.

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