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

Annotations already declare the tool as idempotent and non-destructive, and the description adds behavioral details: it explains that calling with no args returns a link, and providing a token enables session-only login. It doesn't contradict the annotations and adds context about the two operational modes.

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 a single, moderately dense paragraph but remains clear and structured with a 'Best:' vs 'Or' breakdown. It isn't overly verbose, though it could be slightly more organized with breaks; still, it's efficient.

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 tool with one optional parameter and no output schema, the description covers the essential behaviors: how to obtain a link, how to use a token, and the difference between permanent and session logins. It's complete enough for an agent to use correctly.

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?

Although the schema only declares a string 'token', the description fully explains its meaning and optionality: it can be omitted to get a link, or provide a JWT for session login. This goes well beyond the schema and gives clear semantics for the single parameter.

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 purpose: authenticate the user by either providing a JWT token or obtaining a browser login link. It uses specific verbs like 'log in' and 'call with { token } or no args', and it distinguishes this authentication tool from sibling tools like 'connect' or 'marketplace' by focusing solely on authentication.

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 explicit usage context: it explains the two modes (permanent via config header vs session via token parameter) and instructs when to call with no args to get the link. It doesn't explicitly state when NOT to use, but the guidance is clear enough for an agent to decide.

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