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

readOnlyHint=true already tells the agent this is a safe read. The description adds genuinely useful context beyond the annotation: default ordering (newest first), the underlying endpoint GET /contacts, the returned field set, and the fact that results become an envelope { data, pagination } once more pages exist. It does not disclose authentication requirements, rate limits, or the default page size behavior.

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 compact sentences: what it lists and default ordering first, then endpoint and return shape. Nothing is redundant or padded, and the most decision-relevant information is front-loaded.

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, the description carries the burden of describing return values, and it does so concretely by listing key fields and the pagination envelope. What remains unstated — auth requirements and whether filtering is server-side — is minor for a simple read-only list tool.

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 all four parameters (q, page, per_page, created_before) are already documented in the schema, including the preference for created_before over legacy page. The description adds nothing about parameter syntax or semantics, 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 and resource ('List contacts') and adds the domain gloss '(customers/vendors)' plus default ordering 'newest first', which orients an agent immediately. It does not explicitly distinguish itself from quaderno_get_contact or the search-style sibling, so sibling differentiation is left implicit.

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?

The listing intent is clear from the name and description, but there is no explicit guidance on when to prefer this over quaderno_get_contact (single record) or how to narrow results with q. Usage is implied rather than stated.

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