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

Annotations already declare readOnlyHint=false and idempotentHint=false, but the description goes beyond the bare booleans by spelling out the consequence: existing text is preserved and two calls append twice. That is genuinely useful, behavior-defining context the structured fields do not convey, though it says nothing about auth or response behavior.

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 tight sentences with the operation class, semantics, and non-idempotency constraint front-loaded, plus the concrete endpoint at the end. Every clause earns its place and nothing is redundant.

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 two-parameter mutation with full schema coverage and annotations covering the safety profile, the description is nearly complete: it covers preservation semantics and retry hazard. The only omission is what the call returns (no output schema exists), which is a minor gap given the operation's simplicity.

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%, so both `repository` and `body` are already fully documented with format and length constraints. The description adds no additional parameter-level detail, which is the expected baseline when the schema carries the load.

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 (append), resource (repository README), and scope (existing text is kept), which cleanly separates it from siblings like packagecloud_get_readme and packagecloud_create_readme without opening either schema. The leading 'WRITE:' token additionally signals the mutation class immediately.

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 clear context for use — appending to an existing README while preserving current content — and the non-idempotency warning steers the agent away from blind retries. It stops short of explicitly naming an alternative (e.g., use create_readme to replace rather than append), so the routing is implied rather than stated.

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