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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the safety profile is covered. The description adds genuine behavioral context — that card identity and the final four digits are immutable — but says nothing about why the call is flagged destructive, whether omitted fields are preserved, or how retries behave despite an idempotency_key existing.

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, both load-bearing: the first says what can change, the second says what cannot. Nothing redundant and the scope is front-loaded.

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 no explanation. For an 11-parameter mutation tool with a destructive flag, though, the description should say whether the update is partial or a full replace and what the destructive hint implies; those gaps matter more than the two sentences provided.

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 only 36%, and the description names the four field groups that lack schema descriptions (brand, type, dates, cardholder name), which is real compensation. It does not, however, give any date format or say whether null means 'clear' versus 'leave unchanged', and the workspace/conversation/idempotency parameters are left entirely to their schema text.

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 (change) and resource (a card) plus the exact editable fields: brand, type, dates, cardholder name. That is enough to separate it from well_create_card and well_delete_card, though those siblings are never named explicitly.

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?

Usage is only implied: 'Change a card's...' tells the agent this is the modify-existing path rather than create or delete, but there is no explicit when-to-use, no named alternative, and no prerequisite guidance (permissions, whether the card must be active).

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