agent_memory_set

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

With no annotations, the description carries the full burden and does so well: it discloses the opt-in gating requirement, the credential-value refusal, the encryption model (relay-derived key from the API key, relay can read during a request), and the explicit warning that values are NOT encrypted on this machine. That is exactly the security and preconditions context an agent needs.

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?

Front-loaded with the core action, followed by gating and encryption context in compact sentences. The trailing sentence 'Acts as the identity in the local credential store' is somewhat disconnected from the rest and slightly ambiguous, but overall the text is efficient.

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 5-parameter mutation tool with no annotations, no output schema, and full schema coverage, the description covers safety gating, refusal conditions, and encryption behavior well. It omits what happens on overwrite/conflict and is silent on return confirmation, which are minor gaps given no output schema is declared.

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 schema already documents key, value, namespace, ttl, and value_type with their formats and lengths. The description adds no parameter-level detail beyond what the schema provides, so the baseline 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 and resource: 'Store a value in relay-side memory.' This is clearly distinguishable from the sibling read/delete/list operations (agent_memory_get, agent_memory_delete, agent_memory_list) by name alone. It does not explicitly name those siblings, so it falls short of a 5.

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?

Gives concrete when-not conditions: the tool is off by default and refused unless the owner set VOIDLY_MCP_RELAY_ALLOW_MEMORY_WRITES=1, and credential-shaped values are always refused. It does not name alternative tools or describe when to prefer this over, e.g., agent_memory_get, so it stops short of a 5.

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