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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered without the description. The description adds no further behavioral context such as what 'detailed information' includes or what happens on a not-found ID, so it neither adds nor contradicts.

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?

A single clean sentence with no filler and the lookup key front-loaded. It is efficient, though so terse that it leaves no room for the routing or precondition information an agent would benefit from.

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 read-only, single-required-parameter tool with a non-open-world annotation profile and no output schema, the description is close to sufficient. The only real gap is the absence of any hint about what fields are returned or how to disambiguate from the bulk list tools.

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% and the single parameter 'contactId' is already documented as 'The contact ID to look up'. The description restates the same idea with no added syntax, format, or sourcing detail, 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 ('get detailed information about a specific contact') and scopes it to lookup by ID, which separates it from list-style siblings like get_contacts. It does not explicitly name an alternative sibling, so it stops short of the top band.

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 phrase 'by their ID' implies the precondition (you must already have a contact ID) but there is no explicit when-to-use guidance, no mention of when to prefer get_contacts or search_people instead, and no note on behavior for a missing/invalid ID.

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