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

Beyond annotations, the description discloses important behavioral traits: tags are normalized (lowercase, spaces to hyphens) and new tags are registered globally so they appear in app filters. This adds real side-effect context beyond the readOnly/idempotent/destructive hints.

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 sentences with no filler. The core action is front-loaded, and every clause adds useful information about what happens to the tags and where they appear.

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 tool with one required parameter and no output schema, the description covers the operation, resource, and notable side effects. It could mention what the response contains, but that is not essential for correct invocation.

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 schema already documents post_ids, add_tags, and remove_tags. The description adds general tag behavior (normalization, global registration) but no extra per-parameter meaning beyond what the schema provides.

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?

Uses a specific verb phrase 'Add and/or remove custom tags' against a clear resource ('posts of the library (Instagram or TikTok)'). It distinguishes from sibling tools like tag_my_account and delete_tag, and adds concrete behavioral details about normalization and global registration.

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?

The resource scope and tag behavior imply when this tool is appropriate, but nothing explicitly tells an agent when to choose it over alternatives such as tag_my_account or delete_tag. The usage context is clear but not formally stated.

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