extend_stacking

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

With no annotations, the description carries the full burden and does well: it discloses the mutation nature, that increasing 'locks more of the address's unlocked STX', a refusal window (prepare phase), and a hard cycle-bound constraint. It stops short of stating permission/auth requirements or what happens to unspecified stake fields.

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-loads the purpose and operations, then constraints, with no verbose preamble. The trailing 'Tip: call earning_opportunities' is mildly promotional but very short and harmless.

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 mutation tool with no annotations and no output schema, the description covers purpose, parameter interaction, and operating constraints, so an agent can call it correctly. It lacks result/confirmation expectations, which is the only meaningful gap.

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 baseline is 3, but the description adds real semantics: 'Any combination in one call' tells the agent the parameters interact and can be co-applied, and it clarifies that amountIncrease draws from unlocked STX.

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+resource — 'Update an existing PoX-5 stake' — and enumerates the four operations it performs (extend lock, add STX, switch signer manager, change payout calldata). This clearly signals update-of-existing versus create, but no sibling tool is named to contrast with (e.g. stack_stx, unstake_stx).

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?

Provides preconditions ('refused during the prepare phase', max 96 cycles past next cycle) and notes combination usage, which implies when it is applicable. It does not, however, route the agent between this and stack_stx/unstake_stx or say what to do when no existing stake is present.

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