Save RetroAchievements credentials

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

Discloses key behaviors: validation against live API, persistence to config, and enabling future tool calls without env vars. However, it does not mention error handling (e.g., invalid key) or whether it overwrites existing config. Given no annotations, it's fairly transparent but has minor gaps.

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 sentences, each serving a purpose: action, usage rule, fallback. No filler, front-loaded with the main operation. Extremely concise and well-structured.

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?

The description covers purpose, usage, and parameter sources. Lacks details about return values or error behavior, but the tool is simple and the key behaviors are well explained. Completeness is adequate for context.

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 descriptions cover both parameters (100% coverage). The description adds value by reiterating the 'as typed by them' constraint and referencing the key-retrieval URL, which aids in correct parameter values.

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?

The description clearly states the tool's purpose: validating a username and API key against the live API and persisting them to a config file. It distinguishes itself from sibling tools, none of which handle credential saving.

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?

Explicitly instructs to only use values typed by the user, never to guess or fabricate an API key, and provides a fallback URL for obtaining a key. This leaves no ambiguity about when and how to use the tool.

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