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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=false. The description adds useful context beyond those annotations: it states the tool is closed-world within the authenticated user's account and that supplied fields are overwritten without automatic restoration of previous values. It does not explain partial-update semantics or permission requirements, but the safety profile is meaningfully reinforced.

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?

The purpose and safety notes are front-loaded, but the description is dominated by an inline list of roughly sixty activity_type slugs. That reference material would be better placed in an enum or structured reference, and its presence makes the description unnecessarily long and harder to scan.

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?

The definition covers purpose, category slug rules, and destructive overwrite behavior, and an output schema exists so return values need not be explained. However, it does not clarify whether unspecified fields remain unchanged, what permissions are required, or what happens on invalid category slugs, leaving meaningful gaps for a mutation tool.

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. The description adds substantial meaning for the generic `data` object by enumerating valid built-in activity_type slugs and explaining that custom category slugs from tripsy_categories_list are valid only on Activity objects. It does not add detail for trip_id or id beyond the schema, but the activity_type guidance is valuable.

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?

The first sentence states a specific verb, resource, and identifier: 'Update a Tripsy activity by id.' This clearly distinguishes it from sibling verbs like create, delete, list, and show. It does not explicitly name those alternatives, but the core purpose is unambiguous.

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 description gives no when-to-use guidance relative to tripsy_activities_create or tripsy_activities_show, and no prerequisites or exclusions. The long activity_type slug list is parameter reference material, not guidance for selecting this tool over its siblings.

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