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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful context about the returned fields and states it 'Needs the user's Cotlet API key with access to this app,' which is real auth context. It does not describe error behavior or the precise structure beyond field names.

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?

The opening clause 'One contact with email, tax ID, type and tags' is essentially restated by the next sentence 'Returns one contact with the email address... the tax ID, the contact type and tags.' That redundancy costs efficiency, though the usage and auth sentences earn their place.

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 single-record read with 100% schema coverage, no output schema, and annotations covering safety, the description is largely sufficient: it names returned fields, gives usage context, and notes the API key requirement. Only the absence of sibling routing keeps it from being fully complete.

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 single contact_id parameter is fully documented in the schema itself ('Contact ID from list_contacts'). The description adds no additional syntax or provenance beyond what the schema already conveys, so the baseline 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 clear verb+resource ('Returns one contact') and enumerates the returned fields (email, tax ID, type, tags), which distinguishes it from the sibling holded_list_contacts by signaling a single-record fetch. It does not name the sibling, but the singular 'one contact' scope is inferable.

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?

Provides usage context ('Use it before sending to check the address, or before deciding to skip a client by tag') but never names an alternative tool or an explicit when-not condition. The guidance is implied rather than routing the agent against siblings like list_contacts or update_contact.

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