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

Annotations declare destructiveHint=true and idempotentHint=true; the description corroborates idempotency with an explanation ('the same value again changes nothing') and adds audit-logging, token-scope requirements and the return shape {name, effect, updatedAt}. The only gap is that the destructive consequence of 'replace' is left implicit rather than spelled out as overwriting an existing value.

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?

Front-loads the verb and the exclusion first, then scoping rules, then safety properties. Every sentence carries distinct information — no restatement of the name or padding.

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?

Despite six parameters and no output schema, the definition supplies the scoping logic, the token prerequisite, and the explicit return shape including the three possible effect values, so an agent can call and interpret the result without further inference.

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 the baseline is 3, but the description adds real meaning the schema does not: the conditional combination of owner/repo/environment/org that determines the variable's scope, and the admin-token constraint attached to org. That goes beyond the field-level descriptions.

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+resource ('Create or replace an Actions variable') and immediately distinguishes it from the adjacent secret tool by name ('not for secrets — use merjax_set_repo_secret'), which separates it from merjax_set_repo_secret, merjax_set_loop_secret and merjax_delete_variable in the sibling list.

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 explicit routing rules for all three scopes (owner+repo for repo-level, owner+repo+environment for environment-level, org for organisation-level) plus the prerequisite that organisation variables need an admin-scoped token, and names the alternative tool for secret values. When-to-use and when-not-to-use are both covered.

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