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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the safety profile is covered; the description's 'WRITE:' only reinforces that. It adds the POST endpoint, but omits the behaviorally important case of a pre-existing README for a non-idempotent create.

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 short, front-loaded clauses: the operation, the alternative routing, and the endpoint. No filler, and the write semantics come first.

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 create with no output schema and full annotation coverage, the description is nearly complete. The only missing piece is the pre-existing-README behavior, which matters given idempotentHint=false.

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 both parameters are documented in the schema, including the 'user/repo' format and Markdown body. The description adds no syntax, format, or constraint detail beyond that, so the baseline of 3 is appropriate.

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 ('create the Markdown README of a repository') and prefixes it with 'WRITE:' to make the mutation nature unmistakable. It explicitly names the sibling append_readme as the tool it is not, so an agent can differentiate the two without opening either 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?

Gives an explicit routing rule: use append_readme for existing READMEs, implying this tool is for initial creation. However, it does not say what happens when a README already exists (error vs overwrite), which is the key ambiguity for a non-idempotent create.

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