update_session_context

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

With no annotations provided, the description carries the behavioral disclosure burden. It clearly conveys the key non-destructive guarantee (append, not overwrite) and that it operates on existing context, which is meaningful beyond the schema. However, it omits details about idempotency behavior or errors when the session/key is missing, though the core side effect is transparent.

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 description is a single front-loaded sentence: 'Append to existing session context without overwriting.' It contains no filler, immediately states the action and target, and conveys a critical constraint in only seven words.

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 tool has moderate complexity with six parameters, but the schema fully describes each parameter. The description provides the essential append semantics needed for correct invocation. It does not mention error handling or idempotency, but the rich schema covers the input side, making the description sufficient for basic correct use.

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?

All six parameters are described in the schema (100% coverage), so the baseline is 3. The description adds minimal parameter-specific meaning—it reinforces that additional_value is appended—but the schema already says 'Value to append'. No extra param context is provided.

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 description clearly states an append operation on existing session context, with the explicit qualifier 'without overwriting'. This distinguishes it from sibling tools like store_session_context (create) and retrieve_session_context (read), making the purpose 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 phrase 'existing session context' and 'without overwriting' imply the tool should be used for incremental updates to an already-stored context, not for creating new context. It does not explicitly name alternative tools, but the context is clear enough to guide selection among the session-related siblings.

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