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

Annotations already establish readOnly/idempotent/non-destructive, so the bar is lower; the description adds real security-relevant context the annotations do not: seeded values are predictable and visible to MCP clients, and output is not vault-grade. It stops short of describing return format or whether outputs are stored, but for a safe read-only generator this is solid added value.

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?

Two tight sentences with zero filler; the core purpose and the sibling routing are front-loaded and the safety caveat is the final clause.

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?

No output schema exists, yet the definition adequately covers purpose, usage, sibling routing, and the key security caveat. The only minor gap is that nothing describes the response shape, which is low-stakes for a trivial generator.

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 seed, length, and symbols including the determinism caveat on seed. The description's reference to 'seeded' output reinforces the seed parameter but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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+resource ('Generate random or seeded test passwords') and immediately differentiates from the closest sibling by name ('use generate-token for identifiers'). An agent can select this tool over generate-token without opening either schema.

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 names the appropriate use case ('demo login fields') and the alternative tool with the condition that selects it ('generate-token for identifiers'). It also supplies an exclusions-style warning that this is not a secure credential vault.

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