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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful context beyond them: destination creation is admin-only and impossible via any tool, and destinations can be 'disabled with the reason', signalling that a non-active status carries diagnostic text.

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?

Three sentences, zero filler, front-loaded with what is listed before the operational constraints. The parenthetical explanation of 'claude_routine' and the pointer to set_job_callback both earn their space.

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 and no parameters, the description is the only source of return-shape information, and it supplies it fully, including the semantics of each status value and how the result feeds the next tool. Nothing needed to call this 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?

Zero parameters, so the schema carries nothing to misread and the baseline is 4. The description instead documents the shape of the result (name, kind, host, status), which is the more useful information here.

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 ('List where this organisation's job callbacks can go') and enumerates the returned fields — name, kind, host, status — with an inline gloss of the non-obvious enum value 'claude_routine'. It also names the downstream sibling fastero_set_job_callback, so an agent can distinguish it from the many other list_* tools without opening any schema.

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?

It gives a clear use route ('fastero_set_job_callback takes a name from here') and rules out a tempting but impossible action ('An admin adds destinations in Settings → Developers → Callbacks; no tool can add one'), which prevents an agent from hunting for a create tool. It stops short of an explicit when-not against any listed sibling, since no alternative list tool exists.

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