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

Annotations already indicate readOnlyHint=false and idempotentHint=true, so the agent knows it's a mutation. The description adds useful behavioral context: it can either set a session-only token or return a login link, and explains the permanent header alternative. It doesn't mention side effects like token storage or expiration, but the main behavioral traits are disclosed beyond what annotations provide.

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 three sentences and somewhat wordy, starting with 'MCP.AI for IDE agents' which is more context than essential. It delivers the key points but could be more concise and front-loaded. For example, it could simply say 'Returns a login link, or accepts a token for session-only authentication.' It's not excessively long, but not tightly written either.

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 simple authentication tool with one optional parameter and no output schema, the description covers the main behaviors: two modes (token vs no-args), the distinction between permanent and session-only, and the intended audience. It lacks detail on error cases, token format validation, or what the returned link looks like, but these are non-essential for an agent to use the tool correctly. Overall, reasonably complete.

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 schema only lists an optional 'token' string with zero description coverage. The description compensates by explaining exactly how to use the token parameter: call with { token: "<jwt>" } for session login, or call with no arguments to get the link. This fully clarifies the parameter's purpose and optional nature, going well beyond the inactive schema.

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 indicates the tool handles authentication: it explains how to log in via browser, copy the access token, and either configure a permanent header or use a session token. Though the wording is somewhat indirect ('log in in the browser'), the purpose is evident and distinct from siblings like connect or toolkit_info. It could be more explicit that the tool returns a login link or accepts a token, but it's clear overall.

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 explicitly distinguishes between two usage scenarios: for permanent, non-expiring access, add the token to the server config as a header; for session-only login, call this tool with a token or with no args to get a link. It provides clear when-to-use and when-not-to-use guidance, and even names an alternative approach (config header). This is strong usage guidance.

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