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

Strong value-add beyond annotations. While readOnlyHint indicates safe reading, the description crucially discloses that passwords are NOT returned ('without exposing password') and explicitly lists what IS returned (username, TOTP availability)—critical security context annotations cannot 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?

Suffers from redundancy: sentences 1 and 2 ('Look up credentials...' vs 'Searches 1Password...') essentially restate the same operation. The final line 'Returns: Credential info if found' duplicates the previous sentence's return statement with awkward formatting.

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?

Appropriately complete for a simple lookup tool with 1 parameter and an output schema. The description successfully covers the security-relevant output behavior (password masking) that the schema structure alone wouldn't convey.

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?

With 0% schema description coverage, the description compensates well by clarifying that the 'url' parameter represents the domain/URL to match against in the vault ('matching the URL/domain'). Sufficient for a single-parameter tool, though format expectations (e.g., FQDN vs full URL) could be clearer.

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?

Excellent specificity: declares the verb (look up), resource (credentials in 1Password), and scoping (for a URL). Mentioning '1Password' specifically distinguishes this from generic credential stores, and the URL-based lookup differentiates it from the 'login' sibling.

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?

Provides implied usage context (use when you need credentials for a specific URL/domain), but lacks explicit guidance contrasting with the 'login' sibling tool—users might confuse credential retrieval with authentication. No 'when-not-to-use' or alternative recommendations are provided.

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