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

Annotations already declare the write/idempotency profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the description's added value is the 'without rewriting the rest of their style guide' statement, which tells the agent this merges rather than replaces. It does not, however, explain the case-insensitive partial-match removal behavior, which lives only in the schema.

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-loaded with the core action and scoping constraint, then the trigger examples, then the sibling pointer. Slightly run-on in the second sentence but every clause earns its place.

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 simple 4-param, no-output-schema tool, the description covers purpose, trigger, semantics of always/never, and the read alternative. The only omission is removal behavior, which the schema covers adequately.

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 the baseline is 3, but the description adds semantic meaning beyond the schema by explaining what always-rules ('what every post must include or follow') and never-rules ('what must never appear') actually govern. It says nothing about the removeAlways/removeNever parameters, so it is not a full 5.

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 ('Save a standing rule…about their posts or images') and the additive scope 'one rule at a time, without rewriting the rest of their style guide'. This clearly distinguishes it from siblings like save_style_guide, set_image_style, and get_brand_identity which it explicitly names.

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 trigger ('Use it the moment the user says things like…') with concrete example utterances, and routes the agent to get_brand_identity to view current state. Both when-to-use and the read alternative are named.

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