credentials_save

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

With no annotations provided, the description carries the full burden. It discloses two useful behaviors: the credentials file is never committed to git, and entries are scoped to the current MCP account. However, it does not disclose overwrite/idempotency behavior, side effects on existing sessions, or any permission requirements. This is adequate but not rich.

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 four sentences, each providing distinct value: the primary action, git exclusion, intended integration with start_session, and account scoping. It is front-loaded with the purpose and contains no filler or redundancy.

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 5-parameter tool with zero schema descriptions and no annotations, the description covers the core parameters and key behavioral constraints, but leaves two optional parameters unexplained and does not define what a 'URL pattern' constitutes. The output schema exists, which helps, but the missing parameter semantics and pattern ambiguity prevent it from being fully 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?

Schema description coverage is 0%, so the description must compensate entirely. It explains url as a 'URL pattern' and username/password as a 'login/password pair', covering three required parameters. But the optional parameters title and aliases are completely unmentioned, leaving an agent guessing about their meaning and format. This is a significant gap.

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 states a specific verb-resource pair ('Save or update credentials') and adds scope ('for a URL pattern in the local credentials store'), which is far more than a restatement of the tool name. It semantically differentiates from siblings like credentials_remove, credentials_list, and credentials_check by making the write action explicit.

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?

It gives clear context for when to use the tool: to persist login/password pairs for automatic pickup by start_session and to avoid exposing secrets in tool-call arguments. It does not explicitly name alternatives or state when not to use it, so it stops short of full exclusion guidance.

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