Label

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 adds the 'existing feed subscription' precondition, but says nothing about whether re-adding the same label duplicates it, errors, or is a no-op — a real gap given the non-idempotent hint.

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?

A single sentence with no filler, front-loaded with the action. It is efficient, though arguably too terse for a mutation tool with undocumented parameters.

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?

An output schema exists so return values need not be explained, but with 0% parameter coverage, no usage guidance, and no behavioral detail beyond the annotations, the definition leaves an agent guessing about preconditions and duplicate-label behavior.

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 0% with two required parameters, so the description must carry the burden. It loosely maps 'category' and 'feed subscription' to the parameters but gives no format guidance for feed_url (URL? feed ID?) and no clarification on whether the category value must match an existing category name.

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: adding a category label to an existing feed subscription. It is reasonably distinguishable from freshrss_subscribe (creates subscriptions) and freshrss_categories (manages categories), though the phrase 'category label' leaves some ambiguity about whether the category is created or must already exist.

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?

No guidance on when to use this versus freshrss_categories or freshrss_subscribe, and no prerequisites stated (e.g., whether the category must already exist, or whether the feed must already be subscribed). The word 'existing' hints at a precondition but never spells it out.

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