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

Annotations already declare readOnly/idempotent/non-destructive/non-open-world, and the description adds real behavioral context beyond them: members-only articles degrade to metadata only, and supplying lang also pulls an AI summary plus cross-language edition links. It doesn't cover auth or failure modes, keeping it below 5.

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 short sentences, front-loaded with the primary purpose and then the conditional lang behavior and the members-only caveat. No filler, every clause carries information.

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 no output schema, the description does the work of previewing returns (full text, metadata, AI summary, edition links), which is exactly what an agent needs. It omits error/fallback behavior when no identifier is provided, a minor gap for a 3-param tool with no required fields.

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 33% – only lang is documented in the schema, and that description is thorough. The description contributes the id-vs-URL lookup modes, but leaves the relationship between the two (mutually exclusive? which wins? what if neither is given) unstated, so it only partially compensates for the bare id/url properties.

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 ('Full text and metadata of one article') and names the two lookup keys (id or URL), which is enough to separate it from siblings like search_articles and latest_articles. It never explicitly contrasts itself with those siblings, so it stops short of a 5.

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?

Usage is only implied: 'by id or URL' tells the agent this is the direct-lookup tool, so search_articles is the implied alternative when no identifier is known. There is no explicit when-to-use or when-not-to-use statement, and no guidance on what happens when neither id nor url is supplied despite zero required parameters.

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