get_subscription_by_username

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the '[READ]' prefix is largely redundant. Beyond that, the description says nothing about auth requirements, behavior for unknown usernames, or return shape.

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 lines, resource stated first, with no filler sentences. Minor redundancy in restating the name and the read nature, but nothing is bloated.

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 tool with no output schema, minimal documentation is defensible, but the description still omits what the returned subscription represents and how it behaves for a nonexistent username. Adequate rather than complete.

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 a single parameter, so the schema carries the burden entirely. The description adds no extra meaning about username format or constraints, which is the baseline 3 case.

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 clear verb (get) plus resource (subscription) and the lookup key (username), which distinguishes it from get_subscription_by_id and get_subscription_by_short_uuid_protected. It is specific but adds no scope detail beyond the name itself.

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 implied by the required username parameter and the tool name, and the sibling set contains obvious alternatives (by id, by short uuid), but the description never states when to prefer this lookup over them. No exclusions or prerequisites are given.

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