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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine value beyond that by disclosing the return shape (added sources with studocu:// ids) and the partial-failure behavior — some ids may silently not be added, detected by diffing against document_ids. It does not explain why an id might fail (invalid, inaccessible, duplicate), which keeps it from a 5.

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, no waste. The action and its limit are front-loaded, and the verification hint follows in the second sentence where it is most useful.

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 2-parameter mutation tool with full schema coverage, an output schema, and safety annotations, the description covers the essential agent-facing concerns including the silent-partial-success case. What remains unstated (root causes for missing documents, duplicate handling despite idempotentHint) is minor but not entirely negligible.

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 both project_id and document_ids are already fully documented with examples and provenance. The description reinforces that document_ids come from search-documents, but adds no syntax or format detail beyond the schema. Baseline 3 is appropriate when the schema carries the parameter burden.

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?

Specific verb (attach), specific resource (Studocu documents), specific destination (a project as project sources), plus a hard limit of 10. It also implicitly distinguishes itself from search-documents by naming that tool as the source of the ids, so an agent can tell the two apart without opening a schema.

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?

It establishes the workflow context (documents come from search-documents) and the cardinality constraint, which tells an agent when this tool applies. There is no explicit 'do not use when' or comparison against alternatives such as write-artifact or read-detached-document, so it stops short of a full routing guide.

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