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

With readOnlyHint=true already declaring the safety profile, the description adds almost no behavioral context beyond restating the name: no note on what happens for an unknown id, no error semantics, no indication of response shape. Annotations carry nearly all the weight here.

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 six-word, front-loaded sentence with no filler. It is efficient, though its brevity borders on under-specification rather than optimal compression.

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 one-parameter read-only lookup with full schema coverage and readOnlyHint, the essentials are covered. Still, nothing is said about the lookup failing or what the caller receives, which leaves a small gap given there is no output schema.

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 id parameter is fully specified with a UUID pattern in the schema. The description's 'by id' adds no syntax or format detail beyond that, 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 ('Get') and resource ('contact') with the singular scope ('one contact by id'), which implicitly distinguishes it from the sibling list_contacts. It is clear, though it does not name the sibling explicitly.

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 'one contact by id' implies you need an id and want a single record rather than a list, but there is no explicit when-to-use guidance or mention of alternatives such as dialmycalls_list_contacts. Usage is left to inference.

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