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

Annotations already establish readOnly/non-destructive/closed-world, so the description adds genuinely new behavior: results are alphabetical, and archived contacts are excluded unless include_archived=true. It also decodes what bot_contact and business_card actually mean, which is real semantic context rather than a restatement of hints.

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 tight sentences, front-loaded with scope and ordering, then filters, then the default-exclusion caveat. Every clause carries information an agent would otherwise have to guess.

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 five-parameter, no-output-schema read tool, the description covers scope, ordering, filter vocabulary, and default exclusion. Only the pagination/limit behavior is unaddressed, a minor omission rather than a blocking one.

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, and it does well: it explains the meaning of each source enum value and clarifies that include_archived defaults to off. The 'limit' parameter (1-100) is left unexplained, which is the main remaining 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?

States a specific verb and resource ('List the caller's OWN contact book') and pins the scope with 'OWN' plus alphabetical ordering, which separates it from broader directory or search tools without needing to name them.

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?

Implies usage through filter descriptions ('Optionally filter by source/tag/starred') and states the default exclusion behavior, but never says when to prefer this over find_contact_personal, search_personal, or erp_list_contacts, nor any when-not condition.

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