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

Annotations already establish readOnly=true, non-destructive, open-world, so the safety story is covered. The description adds value beyond annotations by disclosing the shape of the return (name, phone, tags, attributes, chat state, last activity), which matters because there is no output schema; it omits failure behavior for a missing/invalid id.

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?

Two short, front-loaded fragments with zero filler; the returned-field list earns its place given no output schema. The trailing raw endpoint ('GET /project/{project_id}/contact/{contact_id}') is marginal for an agent and slightly dilutes an otherwise tight definition.

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 tool with full schema coverage and annotations, the description supplies the one thing structured data lacks — what comes back — and identifies the resource uniquely. Nothing essential to invoking it correctly 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?

There is a single parameter with 100% schema description coverage, including a pattern and an origin hint ('as returned by the list tools'), so the schema does the heavy lifting. The description only restates 'by id' and adds no format, source, or lookup guidance beyond it — baseline 3.

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 ('One contact by id') and enumerates the returned fields, which is more than a restatement of the title. It does not explicitly contrast with the sibling aisensy_find_contact, so the agent must infer that 'by id' vs 'search' is the dividing line.

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 lookup-by-identifier usage, but the description never says when to use it instead of aisensy_find_contact or aisensy_list_campaign_audience, nor does it state prerequisites such as needing a valid id from a list tool (that hint lives only in the schema).

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