Get contact

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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safe read-only profile is covered. The description adds useful behavioral context by disclosing what the record contains (custom data, subscription state) and that the full record is returned, but says nothing about auth requirements, rate limits, or error behavior when the id is unknown.

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?

Four short labeled sections, each one sentence, with the purpose front-loaded and the exclusion placed before the returns/usage notes. Every line carries information and nothing is redundant.

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?

No output schema exists, so the 'Returns' line earns its place by describing the payload, and the description covers purpose, exclusion, and prerequisite for a single-parameter read tool. Nothing an agent needs to select or invoke this tool is missing.

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 there is only one parameter ('id', documented as a Contact UUID). The description adds the notion that the id must already be known but contributes no format, sourcing, or validation detail beyond the schema, 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 (fetch) and resource (one contact by id) and immediately names the scope of what's included — custom data and subscription state. It also explicitly distinguishes itself from the sibling plunk_lookup_contacts, which addresses the most likely confusion.

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 'Not for' section excludes the email-lookup case and names the alternative tool by name, and the 'Use when' section states the prerequisite (you already have a contact id and need the full record). Both when-to-use and when-not-to-use are explicit.

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