get_contact_by_email

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behaviors: the tool returns a 404 error if no contact exists (error handling), specifies the return data shape (id, email, names, etc.), and mentions case-insensitive email matching (implied from schema but reinforced). It doesn't cover rate limits or authentication needs, but provides substantial operational context.

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 description is efficiently structured with three focused sentences and an example. The first sentence states the purpose, the second provides usage guidelines and error handling, and the third specifies the return shape. Every sentence adds essential information with zero waste.

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 single-parameter read operation with no output schema, the description provides complete context: purpose, usage guidelines, error behavior (404), return data structure, and an example. It compensates well for the lack of annotations and output schema, making the tool's operation fully understandable.

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 the schema already fully documents the single 'email' parameter with its type, format, and case-insensitivity. The description adds minimal value beyond the schema (just restating 'email address to look up'), meeting the baseline of 3 for high schema coverage.

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?

The description clearly states the specific action ('Look up a contact by their email address') and resource ('contact'), distinguishing it from siblings like 'get_contact' (likely by ID) and 'list_contacts' (pagination-based). It explicitly names the key differentiator: email-based lookup.

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 description provides explicit guidance on when to use this tool ('agent has an email address... and wants the full contact record without paginating list_contacts'), when not to use it (returns 404 if no contact exists), and alternatives ('use create_contact to add one'). It also contrasts with 'list_contacts' for pagination scenarios.

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