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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, non-destructive, closed-world), so the description's job is to add context, which it does: a 40-entry cap, one-day TTL, MCP-session scoping, and no auth requirement. It does not describe pagination or what happens when the cap/TTL is exceeded, keeping it short of 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?

The return shape and constraints are front-loaded in the first sentence, with the 'not a conversation history' clarification placed immediately after. There is mild redundancy between 'for this MCP session's cart' and 'scoped to this MCP session,' which keeps it from a 5.

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?

With no output schema, the description carries the return-shape burden and does so by describing each entry as key/value/category and capping the result at 40. Together with the TTL and session scope, an agent has enough to call it correctly; only the read-vs-save decision is left unaddressed.

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% and the single optional param (skill_name) is fully documented in the schema, including the fact that it does not filter results. The description adds nothing about the parameter, so the baseline of 3 applies.

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 (returns) and resource (short shopping preferences stored for this session's cart), and explicitly rules out the most likely misreading with 'It is not a conversation history.' It stops short of naming the counterpart sibling (save_memory), which is the one ambiguity an agent would still need to resolve.

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 useful context (scoped to this MCP session, one-day retention, free/no key) that implies when reading is appropriate, but it never states when to call this versus save_memory or get_cart. Usage is inferable rather than instructed.

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