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

readOnlyHint=true already covers the safety profile, but the description adds genuinely new behavior: 'Passwords are redacted', which tells the agent the response is partially masked and no secrets will be returned. That is real context beyond the annotations, though it says nothing about error/not-found behavior or any rate limits.

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?

One dense sentence front-loads the resource and its returned fields, followed by the redaction caveat and the API mapping. Every clause carries information and nothing is padded.

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?

With no output schema, the field enumeration (status, size, CPU/RAM/disk, IPs, network, firewall, tags, volumes, image) usefully stands in for a return-value description, and the redaction note closes the main gap. Only the region-resolution behavior and failure modes are left to the schema, which is acceptable for a read-only getter.

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 both instance_id and region are fully documented in the schema, including the pattern and the CIVO_REGION default. The description adds no syntax or constraint detail beyond the '{id}' placeholder, 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 and single-resource scope ('Fetch one instance') and enumerates the payload fields returned, which cleanly separates it from the sibling civo_list_instances. It also pins the underlying operation as 'Civo: GET /v2/instances/{id}', leaving no ambiguity about what is being fetched.

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?

Usage is only implied: the singular scope and the {id} endpoint make it obvious this is the by-id lookup rather than the list call. There is no explicit 'use this when you already have an id, otherwise use civo_list_instances' routing, nor any mention of prerequisites such as needing the correct region.

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