Sign in to Yandex

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

The description goes well beyond the annotations (readOnlyHint=false, openWorldHint=true) by disclosing that it opens a browser, handles an automatic redirect, may fall back to a URL when local port is unavailable, and that the token lasts about a year. This provides essential behavioral context for an agent.

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 composed of three sentences, each serving a clear purpose: stating the function, explaining the normal flow, and providing fallback plus usage guidance. Every sentence earns its place, and the information is front-loaded with the core purpose.

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 should clarify return values. It does mention the fallback returns a URL, but it does not explicitly describe what a successful call returns. Despite this minor gap, the description thoroughly covers the login flow, token duration, and prerequisites, making it largely 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 input schema provides 100% coverage for the one parameter `oob`, described as 'Force the copy-paste flow instead of the automatic local redirect.' The description does not mention the parameter, but since the schema already fully documents it, no additional value is added, hence the baseline score of 3.

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 'Sign in to Yandex from here' with a specific verb and resource. It also distinguishes itself from sibling tools, especially submit_code, by explaining that this is the primary sign-in flow and submit_code is only used as a fallback for code submission.

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 provides when to use: 'Run this once (the token lasts ~1 year); needed before the data tools if you are not signed in yet.' It also gives conditional guidance for the fallback path when the local port is unavailable, directing the user to submit_code.

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