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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful behavioral context: it explains why revealing the password is acceptable and exactly when it returns null. It does not discuss permissions or auth requirements, but with annotations present this is a reasonable omission.

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?

Three sentences, front-loaded with purpose, followed by a concise rationale and the null-case fallback. Every sentence contributes useful information and there is no 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 simple read tool with a fully described single parameter, readOnly annotation, and no output schema, the description is complete. It explains the return value for the null case and routes the agent to the correct alternative, leaving no critical gap.

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 100%, so the single site_id parameter is fully documented in the schema as a UUID. The description adds no parameter-specific syntax or meaning beyond that, so the baseline of 3 is appropriate.

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 and resource: 'Return the current password of a gated site.' It also distinguishes itself from the sibling set_site_password by naming it as the alternative when no password is set. An agent can tell this is a read operation for an existing password.

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 covers the when-not case ('Returns null when the site is not gated by password or the password predates this feature') and names the alternative tool to use in that case ('then use set_site_password'). This gives a clear condition and routing instruction.

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