bsky_login

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

With no annotations provided, the description carries full burden and adds valuable behavioral context: it discloses that existing sessions are logged out before re-login, and that credentials can be sourced from environment variables if not provided. It doesn't mention rate limits, error conditions, or session persistence details, but provides more than minimal transparency.

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?

The description is well-structured and appropriately sized: a clear purpose statement followed by two behavioral notes in bullet points. Every sentence earns its place with no redundancy or fluff. The information is front-loaded with the core functionality stated first.

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?

Given the tool's complexity (authentication with side effects), no annotations, and an output schema (which handles return values), the description is reasonably complete. It covers the main behavior, parameter handling, and environment integration. However, it lacks details about error cases, session duration, or what the output contains.

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?

The input schema has 0% description coverage, so the description must compensate. It explains that handle/password can be unspecified (None) and will be completed from environment variables, listing the specific variable names and formats. This adds meaningful semantics beyond the schema's basic type definitions, though it doesn't detail validation rules or constraints.

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: 'Blueskyにログインしてセッションを開始します' (Login to Bluesky and start a session). It specifies the verb (login) and resource (Bluesky session), but doesn't explicitly differentiate from sibling tools like bsky_refresh_session or bsky_logout, which would require 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?

The description provides implied usage guidance: it mentions handling existing sessions (logout then re-login) and environment variable fallback for credentials. However, it doesn't explicitly state when to use this vs. alternatives like bsky_refresh_session or bsky_logout, nor does it mention prerequisites or exclusions.

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