CDP: Login

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

Annotations declare readOnlyHint=false and destructiveHint=true, and the description substantially enriches that picture: origin-bound, https-only, password injected server-side and never returned, session-first fallback ordering, and an enumerated set of return statuses. This is behavioral context well beyond the annotation flags.

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?

Front-loads the core action, then layers security constraints, the domain default, and the return contract in tight sentences with zero filler. Every clause carries information an agent needs.

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 present, the description compensates by enumerating return statuses (session_restored|logged_in|filled|no_credential|wrong_origin). Combined with the origin/https/password-handling notes and 0-required-parameter defaults, an agent has everything needed to call it 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?

Schema coverage is 100%, so the schema already documents all 8 parameters including defaults. The description adds only the domain default behavior, which the schema's own 'default: current page' already conveys, so it is largely redundant with the structured fields.

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?

States a specific verb (auto-login) and resource (attached page) using a named credential source (vaulted website credential). It is clearly distinguishable from sibling form-fillers like cdp_type or cdp_inject, which lack the vaulted-credential and session-restore framing.

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?

Gives clear operational context: session-first (restore if present, else fill the form) and 'omit domain to use the current page's domain'. However, it never explicitly says when NOT to use it or names an alternative (e.g. cdp_type for manual credentials), so it stops short of full routing guidance.

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