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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety and idempotency profile is fully covered structurally. The description adds only a list of returned content, which duplicates the output schema rather than disclosing new traits like auth requirements, rate limits, or pagination. Minimal added behavioral value beyond annotations.

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?

A single front-loaded sentence with no filler; the action and its output come first and the id provenance is appended as a qualifying clause. Every clause earns its place.

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 one-parameter read tool with an output schema and full annotations, the description covers purpose, provenance of the id, and returned content. Return-format detail is unnecessary given the output schema, so nothing essential 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 0% and the schema only says a string of 1-300 characters, so the description carries the burden. It meaningfully compensates by explaining that the id is an 'exact day identifier returned by search or list_days', telling the agent precisely where to source the value, though it doesn't describe the id's format.

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 (Fetch) and the resource it returns (published editorial text, dates, primary sources, correction history) for an exact day identifier. It distinguishes itself from siblings by noting the id comes from search or list_days, though the phrase 'day identifier' is slightly ambiguous about whether it fetches the day record or the editorial content.

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?

Clearly routes the agent: use this after obtaining an id from search or list_days, implying it is the retrieval step following discovery. It does not state when-not to use it or contrast further with list_days/list_topics, but the context is clear.

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